#include <iostream>
#include <algorithm>
#include <cstring>
using namespace std;
int ct[500],n,m;
int main() {
	cin >> n >> m;
	for (int i = 0; i < m; i++) {
		int a, b; cin >> a >> b;
		ct[a]++; ct[b]++;
	}
	int oct = 0;
	for (int i = 0; i < n; i++) { if (ct[i] % 2 == 1)oct++; }
	if (oct == 0 || oct == 2)cout << "YES" << endl;
	else cout << "NO" << endl;
	return 0;
}