#include <iostream>
#include <map>
using namespace std;

int main(){
  int n,m;cin>>n>>m;
  map<int,int> A;
  for(int i = 0; m > i; i++){
    int a,b;cin>>a>>b;
    A[--a]++;A[--b]++;
  }
  int odd = 0;
  for(auto x: A){
    odd += x.second%2;
  }
  if(odd == 0 || odd == 2)cout << "YES" << endl;
  else cout << "NO" << endl;
}