#include <bits/stdc++.h>

using namespace std;

typedef vector<int> vec;
typedef vector<vec> mat;

vec mul(const mat& A, const vec& x) {
    int s = x.size();
    vec ret(s, 0);
    for (int i = 0; i < s; i++) {
        for (int j = 0; j < s; j++) {
            ret[i] += A[i][j] * x[j];
        }
    }
    return ret;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n, m;
    cin >> n >> m;
    mat A(n, vec(n, 0));
    for (int i = 0; i < m; i++) {
        int a, b;
        cin >> a >> b;
        a--;
        b--;
        A[a][b] = 1;
        A[b][a] = 1;
    }
    vec x(n, 0);
    x[0] = 1;
    for (int i = 0; i < 5; i++) {
        x = mul(A, x);
    }
    if (x[0] == 0) cout << "NO\n";
    else cout << "YES\n";
    return 0;
}