// domino?
#include<iostream>
using namespace std;

int main(){
    int n, m;
    cin >> n >> m;

    int s[501] = {};

    int a, b;
    for(int i = 0; i < m; i++){
        cin >> a >> b;
        s[a]++;
        s[b]++;
    }

    int odd = 0;
    for(int i = 0; i < n; i++){
        odd += (s[i] % 2);
    }

    if(odd == 0 || odd == 2)    cout << "YES" << endl;
    else                        cout << "NO" << endl;
    
    return 0;
}