diff --git a/yokoo_5.cpp b/yokoo_5.cpp
new file mode 100644
index 0000000..e44abe0
--- /dev/null
+++ b/yokoo_5.cpp
@@ -0,0 +1,73 @@
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+class Cross_product{
+public:
+  Cross_product();
+  Cross_product(int);
+  void ans_of_Cross_product();
+  void output_anser();
+  void output_xy();
+private:
+  vector<int> x_component_of_vector;
+  vector<int> y_component_of_vector;
+  vector<int> anser_cross_product;
+};
+Cross_product::Cross_product(){
+  for(int i=0, j=5;i<3;i++, j+=2){
+    int k=i+j;
+    x_component_of_vector.push_back((j+i)*(3+k));
+    y_component_of_vector.push_back((j+k)*(3+i));
+  }
+}
+Cross_product::Cross_product(int num){
+  for(int i=0, k=4;i<3;i++,k*=3){
+    x_component_of_vector.push_back((num)-(3+k));
+    y_component_of_vector.push_back((num)-(3+i));
+  }
+}
+void Cross_product::output_xy(){
+  cout << "x={";
+  for(int i=0;i<3;i++){
+    cout << x_component_of_vector.at(i);
+    cout << " ";
+  }
+  cout << "}" << endl;
+  cout << "y={";
+  for(int i=0;i<3;i++){
+    cout << y_component_of_vector.at(i);
+    cout << " ";
+  }
+  cout << "}" << endl;
+}
+void Cross_product::ans_of_Cross_product(){
+  for(int i=0, j=1,k=2;i<3;i++,k++,j++){
+    anser_cross_product.push_back((x_component_of_vector.at(j)*y_component_of_vector.at(k))-(x_component_of_vector.at(k)*y_component_of_vector.at(j)));
+    if(i==0)
+      k=-1;
+    if(i==1)
+      j=-1;
+  }
+}
+void Cross_product::output_anser(){
+  for(int i=0;i<3;i++){
+    cout << anser_cross_product.at(i);
+    cout << " ";
+  }
+  cout << endl;
+}
+
+int main(){
+  Cross_product cross;
+  cross.output_xy();
+  cross.ans_of_Cross_product();
+  cross.output_anser();
+  cout << endl;
+  Cross_product cross2(21);
+  cross2.output_xy();
+  cross2.ans_of_Cross_product();
+  cross2.output_anser();
+  return 0;
+}