#include <cstdio>
#include <algorithm>
#include <vector>
#include <queue>
using namespace std;

struct state { int node, prev, prevprev, step; };

int main() {
        int n, m;
        scanf("%d%d", &n, &m);
        vector<vector<int>> g(n);
        for (int i = 0; i < m; i ++) {
                int a, b;
                scanf("%d%d", &a, &b);
                a --, b --;
                g[a].push_back(b);
                g[b].push_back(a);
        }
        vector<vector<bool>> used(n, vector<bool> (6));
        queue<state> q;
        q.push({ 0, -1, -1, 0 });
        used[0][0] = true;
        while (!q.empty()) {
                state p = q.front(); q.pop();
                int u = p.node, s = p.step, prev = p.prev, prevprev = p.prevprev;
                if (s == 5) continue;
                for (auto v : g[u]) if (!used[v][s + 1]) {
                        if ((s + 1 != 5 && v == 0) || v == prevprev) continue;
                        used[v][s + 1] = true;
                        q.push({v, u, prev, s + 1});
                }
        }
        puts(used[0][5] ? "YES" : "NO");
        return 0;
}