#include <bits/stdc++.h>
using namespace std;

using int64 = long long;
using uint64 = unsigned long long;

int main()
{
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int N, M;
    cin >> N >> M;

    vector<int> deg(N, 0);
    for (int i = 0; i < M; i++)
    {
        int a, b;
        cin >> a >> b;

        deg[a]++; deg[b]++;
    }

    int oddCnt = 0;
    for (int i = 0; i < N; i++)
    {
        oddCnt += deg[i] & 1;

        if (oddCnt > 2)
        {
            cout << "NO" << endl;
            return 0;
        }
    }

    cout << "YES" << endl;

    return 0;
}