#include <iostream>
#include <vector>
using namespace std;

int main() {
    int N, M;
    cin >> N >> M;

    vector<int> deg(N, 0);
    for (int i = 0; i < M; i++) {
        int a, b;
        cin >> a >> b;
        deg[a]++; deg[b]++;
    }
    int cnt = 0;
    for (int i = 0; i < N; i++) {
        cnt += deg[i] & 1;
    }
    
    if (cnt <= 2) cout << "YES" << endl;
    else cout << "NO" << endl;

    return 0;
}