#include<iostream>
#include <bits/stdc++.h>

#define ld long double
#define ll long long
#define IO ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
const int N = 1e6 + 5, mod = 998244353;

void doWork() {
    int n, k;
    cin >> n >> k;
    map<string, int> mx;
    cin.ignore();
    while (k--) {
        string s;
        getline(cin, s);
        int cnt = 0;
        reverse(s.begin(), s.end());
        while (s.size() >= 3 && s.substr((int) s.size() - 3) == ":eR") {
            for (int i = 0; i < 4; i++) {
                s.pop_back();
            }
            cnt++;
        }
        mx[s] = max(mx[s], cnt);
    }
    for (auto i: mx) {
        n -= i.second + 1;
    }
    cout << (n >= 0 ? "YES" : "NO");
}

int main() {
    IO
    int t = 1;
    //cin >> t;
    for (int i = 1; i <= t; i++) {
        //  cout << "Case #" << i << ": ";
        doWork();
    }
}