#include <iostream>
#include <vector>
#include <map>
#include <queue>
#include <algorithm>
#define INF 1<<30
using namespace std;
bool Ans = false;
int N, M;
void dfs(vector<vector<int>> v,int prev,int next,int n) {

	//cout << "next = " << next << " n = " << n << endl;

	if (n == N) { return ; }
	for (int i = 0; i < v[next].size();i++) {
		int f = v[next][i];
		if (f == 1 && n + 1 == N) {
			Ans = true;
		}
		if (f != 1 && f != prev) dfs(v,next, f, n + 1);
	}
	return ;
}

int main() {
	cin.tie(0);ios::sync_with_stdio(false);
	cin >> N >> M;
	vector< vector<int>> v(N + 1);
	for (int i = 0; i < M;i++) {
		int a, b; cin >> a >> b;
		v[a].push_back(b);
		v[b].push_back(a);
	}
	dfs(v,0, 1, 0);
	if (Ans) {
		cout << "YES";
	}
	else { cout << "NO"; }
	cout << endl;
	return 0;
}