import sys
from collections import defaultdict

def main():
    sys.setrecursionlimit(1 << 25)
    N, M = map(int, sys.stdin.readline().split())
    adj = defaultdict(set)
    for _ in range(M):
        a, b = map(int, sys.stdin.readline().split())
        adj[a].add(b)
        adj[b].add(a)
    
    if 1 not in adj:
        print("NO")
        return
    
    neighbors_1 = adj[1]
    if len(neighbors_1) < 2:
        print("NO")
        return
    
    for u in neighbors_1:
        for a in adj[u]:
            if a == 1:
                continue
            for b in adj[a]:
                if b == u or b == 1:
                    continue
                for v in adj[b]:
                    if v == u:
                        continue
                    if v in neighbors_1:
                        print("YES")
                        return
    
    print("NO")

if __name__ == "__main__":
    main()