#include <iostream>
using namespace std;
string a;
string b;
float h;
int main(){
cin >> h >> a >> b;
float sum = 0;
for(int i=0;i<a.size();i++){
if(a[i]==b[i]){
sum = sum + 1;
}
}
if(sum/a.size()>=h)
cout << "yes" << endl;
else
cout << "no" << endl;
return 0;
}