def main():
    import sys
    input = sys.stdin.read().split()
    idx = 0
    N = int(input[idx])
    idx += 1
    M = int(input[idx])
    idx += 1

    adj = [set() for _ in range(N + 1)]
    for _ in range(M):
        a = int(input[idx])
        idx += 1
        b = int(input[idx])
        idx += 1
        adj[a].add(b)
        adj[b].add(a)

    neighbors_of_1 = adj[1]
    if len(neighbors_of_1) < 2:
        print("NO")
        return

    S = neighbors_of_1

    for a in neighbors_of_1:
        for b in adj[a]:
            if b == 1 or b == a:
                continue
            for c in adj[b]:
                if c == 1 or c == a or c == b:
                    continue
                for d in adj[c]:
                    if d == 1 or d == a or d == b or d == c:
                        continue
                    if d in S and d != a:
                        print("YES")
                        return

    print("NO")

if __name__ == "__main__":
    main()