#include <bits/stdc++.h>

#define VARNAME(x) #x
#define show(x) cerr << #x << " = " << x << endl

using namespace std;
using ll = long long;
using ld = long double;

template <typename T>
ostream& operator<<(ostream& os, const vector<T>& v)
{
    os << "sz:" << v.size() << "\n[";
    for (const auto& p : v) {
        os << p << ",";
    }
    os << "]\n";
    return os;
}

template <typename S, typename T>
ostream& operator<<(ostream& os, const pair<S, T>& p)
{
    os << "(" << p.first << "," << p.second
       << ")";
    return os;
}


constexpr ll MOD = (ll)1e9 + 7LL;
constexpr ld PI = static_cast<ld>(3.1415926535898);

template <typename T>
constexpr T INF = numeric_limits<T>::max() / 10;


int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    int N, M;
    cin >> N >> M;
    vector<int> dim(N, 0);
    for (int i = 0; i < M; i++) {
        int a, b;
        cin >> a >> b;
        dim[a]++;
        dim[b]++;
    }
    int cnt = 0;
    for (int i = 0; i < N; i++) {
        if (dim[i] % 2 == 1) {
            cnt++;
        }
    }
    cout << (cnt == 0 or cnt == 2 ? "YES" : "NO") << endl;
    return 0;
}