#include<bits/stdc++.h> using namespace std; int s_s(int a){

} int main(){ string a,b; double n,s=0; cin>>n; cin>>a>>b; for(int i=0;i<a.size();i++){ if(a[i]==b[i])s++; }

if(n<=s/a.size())cout<<"yes";
else cout<<"no";

return 0; } //荣泽仁