#include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
#define fi first
#define se second
template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<pll, int> plp;
const ll INF = 1e9+100;
const ll MOD = 1e9+7;
const double EPS = 1e-10;
const bool debug = 0;
//--------------------------------//

int n, m;
vector<int> g[500];
int cnt[500];

int main() {
	cin >> n >> m;
	REP(i, m) {
		int a, b;
		scanf("%d %d", &a, &b);
		g[a].push_back(b);
		g[b].push_back(a);
		cnt[a]++; cnt[b]++;
	}
	
	int odd = 0;
	REP(i, n) {
		if (cnt[i] & 1) odd++;
	}
	
	bool ans = true;
	if (odd > 2 || odd == 1) ans = false;
	
	puts(ans ? "YES" : "NO");
	
	return 0;
}