Connected Components in a Graph

/*
// Sample code to perform I/O:

cin >> name;                            // Reading input from STDIN
cout << "Hi, " << name << ".\n";        // Writing output to STDOUT

// Warning: Printing unwanted or ill-formatted data to output will cause the test cases to fail
*/

// Write your code here

#include<bits/stdc++.h>
using namespace std;
map<int,vector<int> >mp;
map<int,bool>visited;


void dfs(int root)
{
    visited[root]=true;
    for(auto x:mp[root])
    {
        if(!visited[x])
           dfs(x);
    }
    
    return;
}

int main()
{
    int n,e; cin>>n>>e;
    //map<int,vector<int> >mp;
    
    //int storage[n+1];
    for(int i=1;i<=e;i++)
    {
        int a,b; cin>>a>>b;
        mp[a].push_back(b);
        mp[b].push_back(a);
    }
    
    int countr=0;
    
    for(int i=1;i<=n;i++)
    {
        if(!visited[i])
           {
               dfs(i);
               countr++;
           }
    }
    
    cout<<countr<<endl;
    return 0;
    
    
}