#include<bits/stdc++.h>
using namespace std;
const int in=1e5+10;
const int inf=0x3f3f3f3f;
#define LL long long
LL n,x,y;
double p,cnt;
string a,b;
int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin>>p>>a>>b;
	for(int i=0;i<a.size();i++)if(a[i]==b[i])cnt++;
	double ans=cnt/a.size();
	if(ans>=p)cout<<"yes";
	else cout<<"no";
	return 0;
}