#include<iostream>  
#include<string>
using namespace std;
int main()
{
    double n,c=0;
    string s1,s2;
    cin>>n>>s1>>s2;
    for(int i=0;i<s1.size();i++)if(s1[i]==s2[i])c++;
    if(c/s1.size()>=n)cout<<"yes";
    else cout<<"no";
}