#include<bits/stdc++.h> using namespace std; int main() { string a,b; int n,i,j; float k,m=0,v; cin>>k; cin>>a>>b; n=a.length(); for(i=0;i<=n-1;i++) { if(a[i]==b[i]) { m++; } } v=m/n; if(v>=k) { cout<<"yes"; } else { cout<<"no"; } return 0; }