#include <bits/stdc++.h>
using namespace std;

double p;
char a[550];
char b[550];

int main() {
    cin >> p >> a >> b;

    // 计算字符串a的长度
    int len = strlen(a);

    int cnt = 0;
    for (int i = 0;i < len;i++) {
        if (a[i] == b[i]) {
            cnt++;
        }
    }

    double k = cnt * 1.0 / len;
    if (k >= p) {
        cout << "yes" << endl;
    }else {
        cout << "no" << endl;
    }

    return 0;
}