#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)


int N, M;
vector<int> E[101010];
//-----------------------------------------------------------------
unordered_set<int> C[101010];
string solve() {
	for (int i : E[0]) for (int j : E[i]) {
		if (j == 0) continue;
		C[j].insert(i);
	}

	rep(i, 0, N) for (int j : E[i]) {
		if (j < i) continue;
		if (i == 0 || j == 0) continue;

		int num_i = C[i].size();
		if (C[i].count(j)) num_i--;
		int num_j = C[j].size();
		if (C[j].count(i)) num_j--;

		if (num_i == 1 && num_j == 1) {
			int a;
			for (int k : C[i]) if (k != i && k != j) a = k;
			int b;
			for (int k : C[j]) if (k != i && k != j) b = k;
			if (a != b) return "YES";
		}

		if (1 <= num_i && 1 <= num_j) {
			int m = max(num_i, num_j);
			if (2 <= m) return "YES";
		}
	}

	return "NO";
}
//-----------------------------------------------------------------
int main() {
	cin >> N >> M;
	rep(i, 0, M) {
		int A, B;
		scanf("%d %d", &A, &B);
		A--; B--;

		E[A].push_back(B);
		E[B].push_back(A);
	}
	cout << solve() << endl;
}