/* -*- coding: utf-8 -*-
 *
 * 583.cc: No.583 鉄道同好会 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 500;

/* typedef */

/* global variables */

int ges[MAX_N];

/* subroutines */

/* main */

int main() {
  int n, m;
  scanf("%d%d", &n, &m);

  for (int i = 0; i < m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    ges[u]++, ges[v]++;
  }

  int on = 0;
  for (int i = 0; i < n; i++)
    if (ges[i] & 1) on++;

  if (on <= 2) puts("YES");
  else puts("NO");

  return 0;
}