#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;

class DisjointSets
{
public:
    DisjointSets(const int v)
    {
        m_parent.resize(v);
        m_rank.resize(v);
        m_size.resize(v);
        for (int i = 0; i < v; i++) {
            m_parent[i] = i;
            m_rank[i] = 0;
            m_size[i] = 1;
        }
    }

    bool same(const int a, const int b)
    {
        return find(a) == find(b);
    }


    int find(const int a)
    {
        if (m_parent[a] == a) {
            return a;
        } else {
            return m_parent[a] = find(m_parent[a]);
        }
    }

    void unite(const int a_, const int b_)
    {
        const int a = find(a_);
        const int b = find(b_);
        if (a == b) {
            return;
        }
        if (m_rank[a] > m_rank[b]) {
            m_parent[b] = a;
            m_size[a] += m_size[b];
        } else {
            m_parent[a] = b;
            m_size[b] += m_size[a];
        }
        if (m_rank[a] == m_rank[b]) {
            m_rank[b]++;
        }
    }

    int getSize(const int a)
    {
        return m_size[m_parent[a]];
    }

private:
    vector<int> m_parent;
    vector<int> m_rank;
    vector<int> m_size;
};

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