#include <bits/stdc++.h>
using namespace std;
string DNA1,DNA2;
int main(){
	double n;
	int a;
	cin>>n;
	int sum=0;
	cin>>DNA1;
	cin>>DNA2;
	a=max(DNA1.size(),DNA2.size());
	for(int i=0;i<=a;i++){
		if(DNA1[i]==DNA2[i])
			sum++;
	}
	if(sum*1.0/a>=n)
		cout<<"yes"<<endl;
	else
		cout<<"no"<<endl;
	return 0;
}