#include <iostream>
#include <string>
#include <vector>

using namespace std;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    int n, m;
    
    cin >> n >> m;

    vector<vector<int>> line(150000, {0, 0});
    vector<bool> stop(150000, false);

    for (int i = 0; i < m; i++) {
        int s, t;
        cin >> s >> t;
        line[m][0] = s;
        line[m][1] = t;
        stop[s] = !stop[s];
        stop[t] = !stop[t];
    }

    int count = 0;
    string yes = "YES";
    for (int i = 0; i < m; i++) {
        if (stop[line[m][0]] && stop[line[m][1]]) {
            yes = "NO";
            break;
        }
        else if (stop[line[m][0]] || stop[line[m][1]]) {
            count++;
            if (count >= 3) {
                yes = "NO";
                break;
            }
        }
    }

    cout << yes << "\n";
    
    int a;
    cin >> a;
}