#include <iostream>
#include <vector>

using namespace std;

int main() {
  int n, m;
  cin >> n >> m;

  vector<int> deg(n);
  for (int i = 0; i < m; i++) {
    int u, v;
    cin >> u >> v;
    deg[u]++;
    deg[v]++;
  }

  int odd = 0;
  int even = 0;
  for (int i = 0; i < n; i++) {
    even += deg[i] % 2 == 0;
    odd += deg[i] % 2 == 1;
  }
  
  if (odd == 0 || odd == 2) {
    cout << "YES" << endl;
  } else {
    cout << "NO" << endl;
  }
}