import sys
from sys import stdin
from collections import defaultdict

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

    if N < 5:
        print("NO")
        return

    adj = defaultdict(set)
    for _ in range(M):
        u = int(input[idx])
        idx += 1
        v = int(input[idx])
        idx += 1
        adj[u].add(v)
        adj[v].add(u)

    S = adj[1]
    if not S:
        print("NO")
        return

    # Check for possible 5-cycle
    for a in S:
        for b in adj[a]:
            if b == 1:
                continue
            for c in adj[b]:
                if c == 1 or c == a:
                    continue
                for d in adj[c]:
                    if d in S and d not in {a, b, c}:
                        print("YES")
                        return

    print("NO")

if __name__ == "__main__":
    main()