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

struct UnionFind{
    vector<int> par;
    UnionFind(int N) : par(N){
        for(int i = 0; i < N; i++){
            par[i] = -1;
        }
    }
    int root(int x){
        if(par[x] < 0) return x;
        else return par[x] = root(par[x]);
    }
    void unite(int x, int y){
        int rx = root(x);
        int ry = root(y);
        if(rx == ry) return;
        else{
            if(par[rx] > par[ry]) swap(rx, ry);
            par[rx] += par[ry];
            par[ry] = rx;
       }
    }
    bool same(int x, int y){
        return root(x) == root(y);
    }
    void check(){
        for(auto x : par){
            cout << x << " ";
        }
        cout << endl;
    }
};

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    int n, m;
    cin >> n >> m;

    UnionFind UF(n);
    unordered_set<int> st;
    vector<int> G[n];

    for(int i = 0; i < m; i++){
        int a, b;
        cin >> a >> b;
        UF.unite(a, b);
        G[a].push_back(b);
        G[b].push_back(a);

        st.insert(a);
        st.insert(b);
    }

    int p = 1e9;
    bool f = true;
    for(auto x : st){
        if(f){
            p = UF.root(x);
            f = false;
        }else{
            if(p == UF.root(x));
            else{
                cout << "NO" << endl;
                return 0;
            }
        }
    }

    int odd_cnt = 0;
    for(int i = 0; i < n; i++){
        if(G[i].size() % 2) odd_cnt += 1;
    }

    if(odd_cnt <= 2){
        cout << "YES" << endl;
    }else{
        cout << "NO" << endl;
    }

    return 0;
}