#include<iostream>
#include<algorithm>
#include<vector>
#include<string>
#include<utility>
#define REP(i,n) for(int i = 0;i < (n);i++)
#define pb push_back
using namespace std;
const int INF = 1e9;
typedef long long ll;

int main(){
  int n,m;
  cin >> n >> m;
  int a[n]={0};
  REP(i,m){
    int c,d;
    cin >> c >>d;
    a[c]++;
    a[d]++;
  }
  int ki = 0;
  REP(i,n){
    if(a[i]%2 == 1)
      ki++;
  }
  if(ki <= 2)
    cout <<"YES"<< endl;
  else
    cout << "NO" << endl;
  return 0;
}