#include <iostream>
using namespace std;
int main() {
    int N, M, A, B;
    cin >> N >> M;
 
    int P[N];
    for (int i = 0; i < N; i++ ) {
       P[i] = 0;
    }
    for (int i=0; i < M; i++) {
       cin >> A >> B;
       P[A-1] ++; P[B-1] ++;
    }
    int cnt = 0;
    for (int i = 0; i < N; i++ ) {
       if (P[i]%2 != 0) cnt ++;
    }
    // cout << cnt << endl;
    cout << ((cnt == 0 || cnt == 2) ? "YES" : "NO") << endl;
    return 0;
}