#include<bits/stdc++.h>
using namespace std;
int main(){
    double c,ans;
    char a[1000],b[1000];
    int len;
    cin>>c>>a>>b;
    len=strlen(a);
    for(int i=0;i<len;i++)
        if(a[i]==b[i])
            ans++;
    ans/=len;
    if(ans>=c) cout<<"yes"<<endl;
    else cout<<"no"<<endl;
    return 0;
}