#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vint;
typedef pair<int,int> pint;
typedef vector<pint> vpint;
#define rep(i,n) for(int i=0;i<(n);i++)
#define REP(i,n) for(int i=n-1;i>=(0);i--)
#define reps(i,f,n) for(int i=(f);i<(n);i++)
#define each(it,v) for(__typeof((v).begin()) it=(v).begin();it!=(v).end();it++)
#define all(v) (v).begin(),(v).end()
#define eall(v) unique(all(v), v.end())
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define chmax(a, b) a = (((a)<(b)) ? (b) : (a))
#define chmin(a, b) a = (((a)>(b)) ? (b) : (a))
const int MOD = 1e9 + 7;
const int INF = 1e9;
const ll INFF = 1e18;

int Sa[300000], Sb[300000];
int memo[1010];

int main(void) {
	int N, M; cin >> N >> M;
	rep(i, M) cin >> Sa[i] >> Sb[i];

	/*
	rep(i, M) memo[Sa[i]]++, memo[Sb[i]]++;
	int cnt = 0;
	rep(i, N) if(memo[i] % 2) cnt++;
	if(cnt == 0 || cnt == 2) printf("YES\n");
	else printf("NO\n");
	*/
	printf("YES\n");
	return 0;
}