#include<bits/stdc++.h>

using namespace std;




int main()
{	char as[505],bs[505];
	double a,tmp=0;
	cin>>a;
	cin>>as;
	cin>>bs;
	int w=strlen(as);
	for(int i=0;i<=w;++i)
	{
		if(as[i]==bs[i])
		tmp++;
	}
	if(tmp/w*1.0>=a)
		cout<<"yes";
	else
		cout<<"no";
	return 0;
 } 
 '''