#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
#define rep(i,s,e) for(int (i) = (s);(i) <= (e);(i)++)

int main(){
  int N;
  cin >> N;
  int M;
  cin >> M;
  vector<int> cnt(N,0);
  rep(i,0,M - 1){
    int a,b;
    cin >> a >> b;
    cnt[a]++;
    cnt[b]++;
  }

  int ans = 0;
  rep(i,0,N - 1){
    ans += cnt[i] % 2;
  }
  if(ans == 0 || ans == 2){
    cout << "YES" << endl;
  }
  else{
    cout << "NO" << endl; }
}