#define _USE_MATH_DEFINES
#include <algorithm>
#include <cstdio>
#include <functional>
#include <iostream>
#include <cfloat>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
struct edge { int u, v; ll w; };

ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;

int main() {
	int N, M; cin >> N >> M;
	vector<vector<int> > G(N);
	while (M--) {
		int u, v; scanf("%d%d", &u, &v);
		u--; v--;
		G[u].push_back(v);
		G[v].push_back(u);
	}
	for (int t = 0; t < 1000; t++) {
		vector<int> color(N);
		for (int u = 0; u < N; u++)
			color[u] = rand() % 4;
		vector<bool> a(N);
		a[0] = true;
		for (int c = 0; c < 4; c++) {
			vector<bool> _a(N);
			for (int u = 0; u < N; u++)
				if (a[u])
					for (int v: G[u])
						if (color[v] == c)
							_a[v] = true;
			a = _a;
		}
		for (int v: G[0])
			if (a[v]) {
				cout << "YES" << endl;
				return 0;
			}
	}
	cout << "NO" << endl;
}