#include<bits/stdc++.h>
using namespace std;
const int N=1e2*5+10;
char a[N],b[N];
int main()
{
    int res=0;
    double y;
    cin>>y>>a>>b;
    int x;
    x=strlen(a);
    for(int i=0;i<x;i++)
    {
        if(a[i]==b[i])
        {
            res++;
        }
    }
    double n;
    n=res*1.0/x;
    if(n>y)
    {
        cout<<"yes";
    }
    else if(n<y)
    {
        cout<<"no";
    }
    else
    {
        cout<<"yes";
    }
    return 0;
}