#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <numeric>
#include <utility>
#include <tuple>

#define REP(i, a, b) for (int i = int(a); i < int(b); i++)
using namespace std;
using ll = long long int;
using P = pair<int, int>;

// clang-format off
#ifdef _DEBUG_
#define dump(...) do{ cerr << __LINE__ << ":\t" << #__VA_ARGS__ << " = "; PPPPP(__VA_ARGS__); cerr << endl; } while(false)
template<typename T> void PPPPP(T t) { cerr << t; }
template<typename T, typename... S> void PPPPP(T t, S... s) { cerr << t << ", "; PPPPP(s...); }
#else
#define dump(...) do{ } while(false)
#endif
template<typename T> vector<T> make_v(size_t a, T b) { return vector<T>(a, b); }
template<typename... Ts> auto make_v(size_t a, Ts... ts) { return vector<decltype(make_v(ts...))>(a, make_v(ts...)); }
template<typename T> bool chmin(T &a, T b) { if (a > b) {a = b; return true; } return false; }
template<typename T> bool chmax(T &a, T b) { if (a < b) {a = b; return true; } return false; }
template<typename T> void print(T a) { cout << a << endl; }
template<typename T, typename... Ts> void print(T a, Ts... ts) { cout << a << ' '; print(ts...); }
template<typename T> istream &operator,(istream &in, T &t) { return in >> t; }
// clang-format on

class UnionFind {
public:
    vector<int> par;
    int N;
    UnionFind(int n) {
        par.resize(n, -1);
        N = n;
    }
    int Find(int n) {
        return par[n] < 0 ? n : par[n] = Find(par[n]);
    }
    bool Union(int x, int y) {
        x = Find(x);
        y = Find(y);
        if (x == y) return false;
        if (-par[x] > -par[y]) swap(x, y);
        par[y] += par[x];
        par[x] = y;
        N--;
        return true;
    }
    bool Same(int x, int y) {
        return Find(x) == Find(y);
    }
    int size(int x) {
        return -par[Find(x)];
    }
    int size() {
        return N;
    }
};

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n, m;
    cin, n, m;
    vector<int> deg(n, 0);
    UnionFind uf(n);
    REP(i, 0, m) {
        int a, b;
        cin, a, b;
        deg[a]++;
        deg[b]++;
        uf.Union(a, b);
    }
    int cnt = 0;
    int odd = 0;
    REP(i, 0, n) {
        odd += deg[i] % 2;
        cnt += deg[i] == 0;
    }
    if (odd <= 2 && uf.size() == cnt + 1) {
        cout << "YES" << endl;
    } else {
        cout << "NO" << endl;
    }

    return 0;
}