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

int main()
{
	int N, M; cin >> N >> M;
	vector<vector<int>>E(N);
	for (int i = 0; i < M; i++) {
		int a, b; cin >> a >> b;
		E[a].push_back(b);
		E[b].push_back(a);
	}

	int cnt = 0;
	for (int i = 0; i < N; i++) {
		if (E[i].size() % 2)cnt++;
	}

	if (cnt == 2 || cnt == 0)cout << "YES" << endl;
	else cout << "NO" << endl;

    return 0;
}