#include <iostream>
#include <algorithm>
#include <cmath>
using namespace std;

int main(){
    int N, M;
    cin >> N >> M;
    int stop[N];
    for(int i = 0; i < N; i++){
        stop[i] = 0;
    }
    for(int i = 0; i < M * 2; i++){
        int stop_station;
        cin >> stop_station;
        stop[stop_station]++;
    }
    int count = 0;
    for(int i = 0; i < N; i++){
        count += stop[i] % 2;
    }
    if(count <= 2){
        cout << "YES" << endl;
    }else{
        cout << "NO" << endl;
    }
}