#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define mt make_tuple
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
#define pb push_back
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

class UnionFind {
    int cnt;
    vector<int> par, rank, size;
public:
    UnionFind() {}
    UnionFind(int _n) :cnt(_n), par(_n), rank(_n), size(_n, 1) {
        for (int i = 0; i<_n; ++i) par[i] = i;
    }
    int find(int k) {
        return (k == par[k]) ? k : (par[k] = find(par[k]));
    }
    int operator[](int k) {
        return find(k);
    }
    int getSize(int k) {
        return size[find(k)];
    }
    void unite(int x, int y) {
        x = find(x); y = find(y);
        if (x == y) return;
        --cnt;
        if (rank[x] < rank[y]) {
            par[x] = y;
            size[y] += size[x];
        } else {
            par[y] = x;
            size[x] += size[y];
            if (rank[y] == rank[x]) ++rank[x];
        }
    }
    int count() {
        return cnt;
    }
};

bool solve() {
    int N, M;
    cin >> N >> M;
    UnionFind uf(N);
    vi deg(N);
    rep(i, M) {
        int x, y;
        cin >> x >> y;
        uf.unite(x, y);
        deg[x]++;
        deg[y]++;
    }
    int con = N;
    rep(i, N)if (deg[i] == 0)con--;
    if (N - con + 1 != uf.count())return false;

    int odd = 0, even = 0;
    rep(j, N) if(deg[j]){
        if (deg[j] & 1)odd++;
        else even++;
    }
    int num = odd + even;
    if (num != even && odd != 2)return false;
    return true;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    cout << (solve() ? "YES" : "NO") << endl;
}