#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vl = vector<ll>;     using vvl = vector<vl>;

#define REP(i,n) for(ll i = 0; i < (n); ++i)

int main() {
	cin.tie(0);
	ios_base::sync_with_stdio(false);
	cout << fixed << setprecision(50);
	ll n, m; cin >> n >> m;
	vvl g(n);
	vector<pair<ll, ll>> ab;
	REP(i, m) {
		ll a, b; cin >> a >> b;
		a--; b--;
		g[a].push_back(b);
		g[b].push_back(a);
	}
	queue<tuple<ll, ll, ll>> que;
	que.push(tuple<ll, ll, ll>(0, 0, -1));
	while (!que.empty()) {
		ll d, cur, prev;
		tie(d, cur, prev) = que.front(); que.pop();
		if (d > 5) break;
		for (auto e : g[cur]) if (prev != e) {
			if (d + 1 == 5 && e == 0) {
				cout << "YES" << endl;
				return 0;
			}
			que.push(tuple<ll, ll, ll>(d + 1, e, cur));
		}
	}

	cout << "NO" << endl;

	return 0;
}