#include <bits/stdc++.h>

using namespace std;

using ll = long long;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n, m;
    cin >> n >> m;
    vector<int> deg(n, 0);
    for (int i = 0; i < m; i++) {
        int u, v;
        cin >> u >> v;
        deg[u]++;
        deg[v]++;
    }
    int cnt = 0;
    for (int i = 0; i < n; i++) {
        cnt += (deg[i] % 2);
    }
    cout << (cnt <= 2 ? "YES" : "NO") << endl;
    return 0;
}