diff --git a/Dima_and_friends.cpp b/Dima_and_friends.cpp
new file mode 100644
index 0000000..17e2cef
--- /dev/null
+++ b/Dima_and_friends.cpp
@@ -0,0 +1,17 @@
+#include <iostream>
+using namespace std;
+int main(){
+    int n,f,count=0,sum=0,a;
+    cin>>n;
+    for(int i=1;i<=n;i++){
+        cin>>f;
+        sum+=f;
+    }
+    for(int j=1;j<=5;j++){
+        a= sum+j;
+        if(a%(n+1)!=1){
+            count++;
+        }
+    }
+    cout<<count;
+}
\ No newline at end of file
diff --git a/Football2.cpp b/Football2.cpp
new file mode 100644
index 0000000..0968f33
--- /dev/null
+++ b/Football2.cpp
@@ -0,0 +1,23 @@
+#include <iostream>
+#include <string>
+using namespace std;
+int main(){
+    string s;
+    cin>>s;
+    int count=1;
+    for(int i=0;i<s.length();i++){
+        if(s[i]==s[i+1]){
+            count++;
+            if(count==7){
+                cout<<"YES"<<endl;
+                return 0;
+            }
+        }
+        else {
+            count=1;
+        }
+        
+    }
+    cout<<"NO"<<endl;
+    return 0;
+}
\ No newline at end of file
diff --git a/Jzzhu_and_children.cpp b/Jzzhu_and_children.cpp
new file mode 100644
index 0000000..66d66fe
--- /dev/null
+++ b/Jzzhu_and_children.cpp
@@ -0,0 +1,32 @@
+#include <iostream>
+using namespace std;
+int main(){
+    int n,m,pos,arr[101];
+    bool flag=true;
+    cin>>n>>m;
+    pos=n;
+    for(int i=0;i<n;i++){
+        cin>>arr[i];
+    }
+    while(flag)
+    {
+        for(int i=0;i<n;i++){
+            arr[i] -= m;
+            if(arr[i]>0){
+                pos=i+1;
+            }
+        }
+        for(int i=0;i<n;i++){
+            if(arr[i]>0){
+                flag=true;
+                break;
+            }
+            else{
+                flag=false;
+            }
+        }
+    }
+    cout<<pos<<endl;
+
+    
+}
\ No newline at end of file
diff --git a/Little_elephant_2.cpp b/Little_elephant_2.cpp
new file mode 100644
index 0000000..027e69b
--- /dev/null
+++ b/Little_elephant_2.cpp
@@ -0,0 +1,16 @@
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    int n;
+    cin >> n;
+    cout << n;
+    for (int i = 1; i < n; ++i)
+    {
+        cout << " " << i;
+    }
+    cout << endl;
+    return 0;
+}
\ No newline at end of file
diff --git a/Petr_and_book.cpp b/Petr_and_book.cpp
new file mode 100644
index 0000000..e8d4979
--- /dev/null
+++ b/Petr_and_book.cpp
@@ -0,0 +1,21 @@
+#include <iostream>
+using namespace std;
+int main(){
+    int n,pages[8],sum=0;
+    cin>>n;
+    for(int i=1;i<=7;i++){
+        cin>>pages[i];
+    }
+    while(sum<n){
+        for(int i=1;i<=7;i++){
+            sum += pages[i];
+            if(sum>=n){
+                cout<<i;
+                break;
+            }
+        }
+
+    }
+
+    
+}
\ No newline at end of file
diff --git a/R _two.cpp b/R _two.cpp
new file mode 100644
index 0000000..ec244a1
--- /dev/null
+++ b/R _two.cpp	
@@ -0,0 +1,30 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+int main()
+{
+    int n, a1;
+    cin >> n >> a1;
+
+    int prev(a1), cur, reconnaissance(1000), index1, index2;
+    for (int i = 2; i <= n; ++i)
+    {
+        cin >> cur;
+        int diff = abs(cur - prev);
+        if (diff < reconnaissance)
+        {
+            reconnaissance = diff;
+            index1 = i - 1;
+            index2 = i;
+        }
+        prev = cur;
+    }
+    int diff = abs(a1 - prev);
+    if (diff < reconnaissance)
+    {
+        index1 = n;
+        index2 = 1;
+    }
+    cout << index1 << " " << index2 << endl;
+    return 0;
+}
\ No newline at end of file
diff --git a/The_number_of_positions.cpp b/The_number_of_positions.cpp
new file mode 100644
index 0000000..a14f4c7
--- /dev/null
+++ b/The_number_of_positions.cpp
@@ -0,0 +1,7 @@
+#include <iostream>
+using namespace std;
+int main(){
+    int n,a,b,count=0;
+    cin>>n>>a>>b;
+    cout<<min(n-a,b+1);
+}
\ No newline at end of file
diff --git a/Translation.cpp b/Translation.cpp
new file mode 100644
index 0000000..7ae791b
--- /dev/null
+++ b/Translation.cpp
@@ -0,0 +1,15 @@
+#include <iostream>
+#include <string>
+#include <algorithm>
+using namespace std;
+int main(){
+    string s,t;
+    cin>>s>>t;
+    reverse(s.begin(),s.end());
+    if(s==t){
+        cout<<"YES";
+    }
+    else{
+        cout<<"NO";
+    }
+}
\ No newline at end of file
diff --git a/Xenia_and_ringroad.cpp b/Xenia_and_ringroad.cpp
new file mode 100644
index 0000000..ac3aa0e
--- /dev/null
+++ b/Xenia_and_ringroad.cpp
@@ -0,0 +1,18 @@
+#include <iostream>
+using namespace std;
+int main(){
+    long long n,m,loc=1,ans=0;
+    cin>>n>>m;
+    for(int i=0;i<m;i++){
+        int now;
+        cin>>now;
+        if(now>=loc){
+            ans += now-loc;  //because now is greater than loc
+        }
+        else {
+            ans += n-(loc-now);
+        }
+        loc=now;
+    }
+    cout<<ans;
+}
\ No newline at end of file
diff --git a/airport.cpp b/airport.cpp
new file mode 100644
index 0000000..e865b5d
--- /dev/null
+++ b/airport.cpp
@@ -0,0 +1,34 @@
+#include <iostream>
+#include <algorithm>
+using namespace std;
+int main(){
+    int n,m,a[1000];
+    cin>>n>>m;
+    for(int i=0;i<m;i++){
+        cin>>a[i];
+    }
+    sort(a,a+m);
+    int min=0,no=a[0],k=0;
+    for(int i=0;i<n;i++){
+        min += no;
+        no -= 1;
+        if(no==0){
+            no=a[++k];
+        }
+    }
+    sort(a,a+m,greater<int>());
+    int max=0;
+    while(n--){
+        max += a[0];
+        a[0] -= 1;
+        for(int i=1;i<m;i++){
+            if(a[i]<=a[i-1]){
+                break;
+            }
+            swap(a[i],a[i-1]);
+        }
+    }
+    cout<<max<<" "<<min<<endl;
+    return 0;
+
+}
\ No newline at end of file
diff --git a/bicycle_chain.cpp b/bicycle_chain.cpp
new file mode 100644
index 0000000..06c69e3
--- /dev/null
+++ b/bicycle_chain.cpp
@@ -0,0 +1,27 @@
+#include <iostream>
+using namespace std;
+int main(){
+    int n,m,a[50],max=0,count=1,b;
+    cin>>n;
+    for(int i=0;i<n;i++){
+        cin>>a[i];    
+    }
+    cin>>m;
+    for(int i=0;i<m;i++){
+        cin>>b;
+        for(int j=0;j<n;j++){
+            if(b%a[j]==0){
+                int x = b/a[j];
+                if(x>max){
+                    max=x;
+                    count=1;
+                }
+                else if(x==max){
+                    count+=1;
+                }
+                break;
+            }
+        }
+    }
+    cout<<count;
+}
\ No newline at end of file
diff --git a/buisness_trip.cpp b/buisness_trip.cpp
new file mode 100644
index 0000000..768f73f
--- /dev/null
+++ b/buisness_trip.cpp
@@ -0,0 +1,28 @@
+#include <iostream>
+#include <algorithm>
+using namespace std;
+int main(){
+    int k,sum=0,arr[12],count=0,total=0;
+    cin>>k;
+    for(int i=0;i<12;i++){
+        cin>>arr[i];
+        total+=arr[i];
+    }
+    sort(arr,arr+12,greater<int>());
+    if(total<k){
+        cout<<-1;
+    }
+    else if(k==0){
+        cout<<0;
+    }
+    else{
+        for(int i=0;i<12;i++){
+            sum+=arr[i];
+            count++;
+            if(sum>=k){
+                cout<<count;
+                break;
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/chat_room.cpp b/chat_room.cpp
new file mode 100644
index 0000000..748bef9
--- /dev/null
+++ b/chat_room.cpp
@@ -0,0 +1,26 @@
+#include <iostream>
+#include <algorithm>
+#include <string>
+using namespace std;
+int main(){
+    string a,b="hello";
+    int l,j=0,count=0;
+    cin>>a;
+    l=a.length();
+    for(int i=0;i<l;i++){       //try a[i]==b[j]
+        if(a[i]==b[j]){
+            j++;
+            count++;
+        
+            if(count==5){
+                break;
+            }
+        }
+    }
+    if(count==5){
+        cout<<"YES";
+    }
+    else{
+        cout<<"NO";
+    }
+}
\ No newline at end of file
diff --git a/dragons.cpp b/dragons.cpp
new file mode 100644
index 0000000..e9ac4a0
--- /dev/null
+++ b/dragons.cpp
@@ -0,0 +1,27 @@
+#include <iostream>
+#include <algorithm>
+using namespace std;
+int main(){
+    int s,n,count=0;
+    pair<int, int>a[1000];
+    cin>>s>>n; //s=2
+    int c=s; //c=2
+    for(int i=0;i<n;i++){
+        cin>>a[i].first>>a[i].second;
+    }
+    sort(a,a+n);
+    for(int i=0;i<n;i++){
+        if(a[i].first>=c){
+            cout<<"NO";
+            break;
+        }
+        else {
+            c=c+a[i].second;
+            count++;
+        }
+    }
+
+    if(count==n){
+        cout<<"YES";
+    }
+}
\ No newline at end of file
diff --git a/dubstep.cpp b/dubstep.cpp
new file mode 100644
index 0000000..6ebb4b3
--- /dev/null
+++ b/dubstep.cpp
@@ -0,0 +1,24 @@
+#include <iostream>
+#include <string>
+using namespace std;
+ int main(){
+    string s;
+    cin>>s;
+    int count=1;
+    int l=s.length();
+    for(int i=0;i<l;){
+        if(s[i]=='W' && s[i+1]=='U' && s[i+2]=='B'){
+            i+=3;
+            if(!count){
+                cout<<" ";
+                count=1;
+            }
+            continue;
+        }
+        else {
+            cout<<s[i];
+            i++;
+            count=0;
+        }
+    }
+ }
\ No newline at end of file
diff --git a/effective_approach.cpp b/effective_approach.cpp
new file mode 100644
index 0000000..3c8014a
--- /dev/null
+++ b/effective_approach.cpp
@@ -0,0 +1,25 @@
+#include <cstdio>
+
+int main()
+{
+    int n, a, index[100001];
+    scanf("%d", &n);
+    for (int i = 1; i <= n; ++i)
+    {
+        scanf("%d", &a);
+        index[a] = i;
+    }
+
+    int m, b;
+    scanf("%d", &m);
+    long long Vasya(0), Petya(0);
+    while (m--)
+    {
+        scanf("%d", &b);
+        Vasya += index[b];
+        Petya += (n + 1 - index[b]);
+    }
+    printf("%I64d %I64d\n", Vasya, Petya);
+    return 0;
+
+}
\ No newline at end of file
diff --git a/even_odds.cpp b/even_odds.cpp
new file mode 100644
index 0000000..8d7bfec
--- /dev/null
+++ b/even_odds.cpp
@@ -0,0 +1,35 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int main()
+{
+    long long n,k,part,output;
+   
+    cin>>n>>k;
+
+    if(n%2==0)
+    {
+        part=n/2;
+    }
+    else
+    {
+        part=(n/2)+1;
+    }
+
+    if(k<=part)
+    {
+        output=(2*k)-1;
+    }
+    else
+    {
+        output=(k-part)*2;
+    }
+
+    cout<<output<<endl;
+
+
+
+    return 0;
+}
+
diff --git a/football.cpp b/football.cpp
new file mode 100644
index 0000000..88c89eb
--- /dev/null
+++ b/football.cpp
@@ -0,0 +1,24 @@
+#include <iostream>
+#include <string>
+using namespace std;
+int main(){
+    int n,ck=1,dk=0;
+    string arr,brr,crr;
+    cin>>n>>arr;
+    for(int i=1;i<n;i++){
+        cin>>brr;
+        if(brr==arr){
+            ck++;
+        }
+        else{
+            crr=brr;
+            dk++;
+        }
+    }
+    if(ck>dk){
+        cout<<arr;
+    }
+    else{
+        cout<<crr;
+    }
+}
\ No newline at end of file
diff --git a/hexadecimal_theorem.cpp b/hexadecimal_theorem.cpp
new file mode 100644
index 0000000..c98f049
--- /dev/null
+++ b/hexadecimal_theorem.cpp
@@ -0,0 +1,8 @@
+#include <iostream>
+using namespace std;
+int main(){
+    long long n;
+    cin>>n;
+    cout<<0<<" "<<0<<" "<<n;
+
+}
\ No newline at end of file
diff --git a/jeff_and_digits.cpp b/jeff_and_digits.cpp
new file mode 100644
index 0000000..d11f91c
--- /dev/null
+++ b/jeff_and_digits.cpp
@@ -0,0 +1,31 @@
+#include <iostream>
+using namespace std;
+int main(){
+    int t,n,z=0,f=0;
+    cin>>n;
+    for(int i=0;i<n;i++){
+        cin>>t;
+        if(t==0){
+            z++;
+        }
+        else if(t==5){
+            f++;
+        }
+    }
+    if(z==0){
+        cout<<-1<<endl;
+    }
+    else if(f<9){
+        cout<<0<<endl;
+    }
+    else{
+        f -= f%9;
+        for(int i=0;i<f;i++){
+            cout<<5;
+        }
+        for(int i=0;i<z;i++){
+            cout<<0;
+        }
+    }
+    return 0;
+}
\ No newline at end of file
diff --git a/k_string.cpp b/k_string.cpp
new file mode 100644
index 0000000..1c6b900
--- /dev/null
+++ b/k_string.cpp
@@ -0,0 +1,32 @@
+#include <iostream>
+#include <algorithm>
+using namespace std;
+//don't copy it directly, even if you don't understand it try to solve this one by taking a example and solve it in your copy
+int main() {
+	int k,count=0;
+	char ch;
+	cin>>k;
+	string s;
+	cin>>s;
+	int l=s.length();
+	sort(s.begin(),s.end());
+	for(int i=0;i<s.length();i++){
+	    if(i%k==0){
+	       ch=s[i]; 
+	    }
+	    if(s[i]==ch){
+	        count++;
+	    }
+	}
+	if(l==count && count%k==0){
+	    for(int i=0;i<k;i++){
+	        for(int l=0;l<s.length();l+=k){
+	            cout<<s[l];
+	        }
+	    }
+	}else{
+	    cout<<"-1";
+	}
+
+	return 0;
+}
\ No newline at end of file
diff --git a/little_elephant_and_rozdil.cpp b/little_elephant_and_rozdil.cpp
new file mode 100644
index 0000000..b777721
--- /dev/null
+++ b/little_elephant_and_rozdil.cpp
@@ -0,0 +1,26 @@
+#include <iostream>
+using namespace std;
+int main(){
+    long long n;
+    int count=1,index,min=1000000001;
+    cin>>n;
+    for(int i=1;i<=n;i++){
+        int a;
+        cin>>a;
+        if(a<min){
+            min=a;
+            index=i;
+            count =1;
+        }
+        else if(a==min){
+            count++;
+        }
+    }
+    if(count==1){
+        cout<<index;
+    }
+    else{
+        cout<<"Still Rozdil";
+    }
+    
+}
\ No newline at end of file
diff --git a/magic_numbers.cpp b/magic_numbers.cpp
new file mode 100644
index 0000000..46eae1d
--- /dev/null
+++ b/magic_numbers.cpp
@@ -0,0 +1,29 @@
+#include <iostream>
+using namespace std;
+int main(){
+    string s;
+    cin>>s;
+    long long l =s.length();
+    bool flag = true;
+    for(int i=0;i<l;){
+        if(s[i]=='1' && s[i+1]=='4' && s[i+2]=='4'){
+            i+=3;
+        }
+        else if(s[i]=='1' && s[i+1]=='4'){
+            i+=2;
+        }
+        else if(s[i]=='1'){
+            i++;
+        }
+        else{
+            flag=false;
+            break;
+        }
+    }
+    if(flag){
+        cout<<"YES";
+    }
+    else{
+        cout<<"NO";
+    }
+}
\ No newline at end of file
diff --git a/parellelepiped.cpp b/parellelepiped.cpp
new file mode 100644
index 0000000..fae18f7
--- /dev/null
+++ b/parellelepiped.cpp
@@ -0,0 +1,13 @@
+#include <iostream>
+#include <math.h>
+using namespace std;
+int main(){
+    int x,y,z;
+    double a,b,c;
+    cin>>x>>y>>z;
+    a = sqrt((x*y)/z);
+    b = sqrt((x*z)/y);
+    c = sqrt((y*z)/x);
+    int total_length = (a+b+c)*4;
+    cout<<total_length;
+}
\ No newline at end of file
diff --git a/present_from_lena.cpp b/present_from_lena.cpp
new file mode 100644
index 0000000..4f2ea1b
--- /dev/null
+++ b/present_from_lena.cpp
@@ -0,0 +1,42 @@
+#include<iostream>
+
+using namespace std;
+
+int main()
+{
+     int i, j, k, l, n;
+     cin >> n;
+     for(i=0;i<=n;i++)
+        {
+            for(j=i;j<n;j++)
+                cout<<"  ";
+            for(k=0;k<=i;k++){
+                    cout << k;
+                    if(i!=0)
+                        cout << " ";
+                 }
+             for(k=i-1;k>=0;k--){
+                cout<<k;
+                 if(k>0)
+                    cout<<" ";
+            }
+            cout<<"\n";
+         }
+      for(i=n-1;i>=0;i--)
+      {
+        for(j=n-1;j>=i;j--)
+          cout<<"  ";
+        for(k=0;k<=i;k++){
+                cout << k;
+                if(i!=0)
+                    cout << " ";
+             }
+         for(k=i-1;k>=0;k--){
+            cout<<k;
+             if(k>0)
+                cout<<" ";
+        }
+        cout<<"\n";
+      }
+     return 0;
+}
\ No newline at end of file
diff --git a/puzzles.cpp b/puzzles.cpp
new file mode 100644
index 0000000..10f8777
--- /dev/null
+++ b/puzzles.cpp
@@ -0,0 +1,19 @@
+#include <iostream>
+#include <algorithm>
+using namespace std;
+int main(){
+    int n,m,p[50],count=0;
+    cin>>n>>m;
+    for(int i=0;i<m;i++){
+        cin>>p[i];
+    }
+    sort(p,p+m);
+    int lmax= p[n-1]-p[0]; //first n checked
+    for(int i=0;i<m-n;i++){        //p[0] already checked
+        if(p[n+i]-p[i+1] < lmax){
+            lmax = p[n+i]-p[i+1];
+        }
+    }
+    cout<<lmax;
+
+}
\ No newline at end of file
diff --git a/sale.cpp b/sale.cpp
new file mode 100644
index 0000000..23cd3cc
--- /dev/null
+++ b/sale.cpp
@@ -0,0 +1,18 @@
+#include <iostream>
+#include <algorithm>
+using namespace std;
+int main(){
+    int n,m,arr[101],sum=0;
+    cin>>n>>m;
+    for(int i=0;i<n;i++){
+        cin>>arr[i];
+    }
+    sort(arr,arr+n);
+    for(int i=0;i<m;i++){
+        if(arr[i]<0){
+            sum+=arr[i];
+        }
+    }
+    cout<<-1*sum;
+    
+}
\ No newline at end of file
diff --git a/string_task.cpp b/string_task.cpp
new file mode 100644
index 0000000..b4acb04
--- /dev/null
+++ b/string_task.cpp
@@ -0,0 +1,18 @@
+#include <iostream>
+#include <string>
+#include <algorithm>
+using namespace std;
+int main(){
+    string s;
+    cin>>s;
+    for(int i=0;i<s.length();i++){
+        if( s[i]=='a' || s[i]=='e'|| s[i]=='i' || s[i]=='o' || s[i]=='u' || s[i]=='y' || s[i]=='A' || s[i]=='E' || s[i]=='I' || s[i]=='O' || s[i]=='U' || s[i]=='Y'){
+            cout<<"";
+        }
+        else{
+            string s1;
+            s1 = tolower(s[i]);
+            cout<<'.'<<s1;
+        }
+    }
+}
diff --git a/supercentral_point.cpp b/supercentral_point.cpp
new file mode 100644
index 0000000..b595f50
--- /dev/null
+++ b/supercentral_point.cpp
@@ -0,0 +1,49 @@
+#include <iostream>
+    using namespace std;
+    int main()
+    {
+        int n , z = 0;
+        bool r , l , u , d ;
+        r = l = u = d = 0;
+
+        cin >> n;
+        int arr[n][2];
+
+        for (int i = 0 ; i < n ; ++i)
+            cin >> arr[i][0] >> arr[i][1];
+
+        for (int i = 0 ; i < n ; ++i)
+            {
+                for (int j = 0 ; j < n ; ++j)
+                    {
+                        if (i == j)
+                            continue ;
+
+                        // right
+                        if (arr[j][0] > arr[i][0] && arr[i][1] == arr[j][1])
+                            r = 1;
+
+                        // left
+                        if (arr[j][0] < arr[i][0] && arr[i][1] == arr[j][1])
+                            l = 1;
+
+                        // up
+                        if (arr[j][0] == arr[i][0] && arr[i][1] < arr[j][1])
+                            u = 1;
+
+                        // down
+                        if (arr[j][0] == arr[i][0] && arr[i][1] > arr[j][1])
+                            d = 1;
+                    }
+
+                if (r == 1 && d==1 && l==1 && u==1)
+                    ++z;
+
+                r = l = u = d = 0;
+            }
+
+            cout << z << endl;
+
+        return 0 ;
+
+    }
diff --git a/system_of_equations.cpp b/system_of_equations.cpp
new file mode 100644
index 0000000..327ae06
--- /dev/null
+++ b/system_of_equations.cpp
@@ -0,0 +1,16 @@
+#include <iostream>
+using namespace std;
+int main(){
+    int n,m,count=0;
+    cin>>n>>m;
+    for(int i=0;i<=n;i++){
+        for(int j=0;j<=m;j++){
+            int x = (i*i)+j;
+            int y = i+(j*j);
+            if(x==n && y==m){
+                count++;
+            } 
+        }
+    }
+    cout<<count;
+}
\ No newline at end of file