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

#define lint long long
#define P pair<int, int>
#define LLP pair<long long, long long>
#define REP(i, x, n) for(int i = (x), i##_len = (int)(n) ; i < i##_len ; ++i)
#define rep(i, n) for(int i = 0, i##_len = (int)(n) ; i < i##_len ; ++i)
#define repr(i, n) for(int i = (int)(n) - 1 ; i >= 0 ; --i)
#define SORT(x) sort((x).begin(), (x).end())
#define SORT_INV(x) sort((x).rbegin(), (x).rend())

const int IINF = 1e9 + 10;
const long long LLINF = (long long)1e18 + 10;
const long long MOD = (long long)1e9 + 7;
const int dx4[] = {1, 0, -1, 0}, dy4[] = {0, 1, 0, -1};
const int dx8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dy8[] = {0, -1, -1, -1, 0, 1, 1, 1};
const double EPS = 1e-8;

vector< vector<int> > g;
vector<bool> done;

void dfs(int v){
    done[v] = true;
    for(auto x : g[v]){
        if(!done[x]){
            dfs(x);
        }
    }
    return;
}

int main(){

    cin.tie(0);
    ios::sync_with_stdio(false);

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

    g.resize(n);
    vector<int> deg(n);
    vector<bool> v(n);
    rep(i, m){
        int a, b;
        cin >> a >> b;
        g[a].push_back(b);
        g[b].push_back(a);
        ++deg[a];
        ++deg[b];
        v[a] = true;
        v[b] = true;
    }

    int cnt = 0;
    rep(i, n){
        cnt += deg[i] % 2;
    }

    bool ans = cnt <= 2;
    
    done.resize(n, false);
    bool flag = false;
    rep(i, n){
        if(v[i] && !flag && !done[i]){
            dfs(i);
            flag = true;
        }else if(v[i] && flag && !done[i]){
            ans = false;
            break;
        }
    }

    if(ans){
        cout << "YES" << endl;
    }else{
        cout << "NO" << endl;
    }

    return 0;

}