#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll = long long;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n, m, r;
    cin >> n >> m;
    vector<int> cnt(n);
    atcoder::dsu uf(n);
    for(int i = 0; i < m; i++){
        int u, v;
        cin >> u >> v;
        r = u;
        uf.merge(u, v);
        cnt[u]++, cnt[v]++;
    }
    cout << (count_if(cnt.begin(), cnt.end(), [&](int v){return (v & 1);}) <= 2 && uf.size(r) == count_if(cnt.begin(), cnt.end(), [&](int v){return v >= 1;}) ? "YES" : "NO") << '\n';
}