#include <bits/stdc++.h>

using namespace std;

int A[20000][20000];
int x[20000];
int ret[20000];

void mul(int A[20000][20000], int* x, int n) {
    for (int i = 0; i < n; i++) {
        ret[i] = 0;
        for (int j = 0; j < n; j++) {
            ret[i] += A[i][j] * x[j];
        }
    }
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n, m;
    cin >> n >> m;
    for (int i = 0; i < m; i++) {
        int a, b;
        cin >> a >> b;
        a--;
        b--;
        A[a][b] = 1;
        A[b][a] = 1;
    }
    for (int i = 0; i < n; i++) x[i] = A[0][i];
    for (int i = 0; i < 4; i++) {
        memcpy(ret, x, sizeof(int) * 20000);
    }
    if (x[0] == 0) cout << "NO\n";
    else cout << "YES\n";
    return 0;
}