#include<bits/stdc++.h>
using namespace std;
int main(){
  int n,m;
  cin>>n>>m;
  int a,b;
  vector<int> t(n,0);
  for(int i=0;i<m;++i){
    cin>>a>>b;
    t[min(a,b)-1]++;
    t[max(a,b)-1]--;
  }
  for(int i=0;i<n;++i){
    if((i&&(t[i]+=t[i-1])%2)||(t[i]%2))return cout<<"NO",0;
  }
  cout<<"YES";
}