#include<bits/stdc++.h> using namespace std; int main(){ float t; cin>>t; int cnt=0; char a[502],b[502]; int l=0; cin>>a>>b; while(a[i]!=''){ l++; } for(int i=0;i<l;i++){ if(a[i]==b[i]) cnt++; } if(cnt*1.0/l>=t) cout<<"yes"; else cout<<"no"; return 0; }