#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;

struct UnionFind {
    vector<int> data;
    int __size;
    UnionFind(int size) : data(size, -1), __size(size) { }
    bool unionSet(int x, int y) {
        if ((x = root(x)) != (y = root(y))) {
            if (data[y] < data[x]) swap(x, y);
            data[x] += data[y]; data[y] = x; __size--;
        }
        return x != y;
    }
    bool findSet(int x, int y) { return root(x) == root(y); }
    int root(int x) { return data[x] < 0 ? x : data[x] = root(data[x]); }
    int size(int x) { return -data[root(x)]; }
    int size() { return __size; }
};

bool euler_path(vector<vector<int>> &g) {
    vector<int> cnt(2);
    for (auto &v: g) cnt[v.size() % 2]++;
    return cnt[1] == 0 || cnt[1] == 2;
}

int main() {
    int n, m; cin >> n >> m;
    vector<vector<int>> g(n);
    UnionFind uf(n);
    while (m--) {
        int a, b; cin >> a >> b;
        g[a].emplace_back(b);
        g[b].emplace_back(a);
        uf.unionSet(a, b);
    }
    int cnt = 0;
    for (int i = 0; i < n; i++) {
        if (uf.root(i) != i) continue;
        if (uf.size(i) == 1) continue;
        cnt++;
    }
    cout << (euler_path(g) && cnt == 1 ? "YES" : "NO") << endl;
    return 0;
}