import std.stdio;
import std.typecons;
import std.string;
import std.array;
import std.conv;
import std.container;

void main() {
    int N, M;
    readf("%d %d\n", &N, &M);
    auto G = new int[][](N);
    foreach (i; 0 .. M) {
        int a, b;
        readf("%d %d\n", &a, &b);
        a--; b--;
        G[a] ~= b;
        G[b] ~= a;
    }

    alias S = Tuple!(int, "index", int, "depth", int, "prev");
    bool[S] D;
    D[S(0, 0, -1)] = true;
    DList!S Q;
    Q.insert(S(0, 0, -1));
    while (!Q.empty) {
        auto c = Q.front; Q.removeFront;
        int v = c[0];
        int d = c[1];
        int prev = c[2];
        if (d >= 5) continue;
        foreach (nv; G[v]) {
            if (nv == prev) continue;
            int nd = d + 1;
            if (S(nv, nd, v) in D) continue;
            D[S(nv, nd, v)] = true;
            Q.insert(S(nv, nd, v));
        }
    }
    foreach (k, v; D) {
        if (k.index == 0 && k.depth == 5) {
            writeln("YES"); return;
        }
    }
    writeln("NO");
}