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

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

bool is_connected(UnionFind & uf){
    int root = -1;
    for (int i = 0; i < uf.data.size(); ++i){
        int r = uf.root(i);
        if (r == i) continue;
        if (root == -1){
            root = r;
        }else if (root != r){
            return false;
        }
    }
    return true;
}

bool has_one_stroke_path(const vector<int> & degree){
    int count_1 = 0;
    for (auto & d : degree){
        if (d & 1) ++count_1;
    }
    if (count_1 == 0 or count_1 == 2){
        return true;
    }else{
        return false;
    }
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int N, M;
    cin >> N >> M;
    vector<int> degree(N, 0);
    UnionFind uf(N);
    for (int i = 0; i < M; ++i){
        int a, b;
        cin >> a >> b;
        ++degree[a];
        ++degree[b];
        uf.unite(a, b);
    }
    if (is_connected(uf) and has_one_stroke_path(degree)){
        cout << "YES" << endl;
    }else{
        cout << "NO" << endl;
    }
    return 0;
}