def read_data():
    N, M = map(int, input().split())
    Es = [set() for i in range(N)]
    for i in range(M):
        a, b = map(int, input().split())
        a -= 1
        b -= 1
        Es[a].add(b)
        Es[b].add(a)
    return N, M, Es

def solve(N, M, Es):
    '''
    Es に頂点0を含む長さ5 の単純閉路が存在するか否かを返す。
    '''
    d1 = Es[0]
    d2 = set()
    for d1i in d1:
        d2 |= Es[d1i]
    bss = [d1 & Esb for Esb in Es]
    for c in d2:
        for d in Es[c]:
            if d in d2:
                if is_valid(c, d, bss):
                    return True
    return False

def is_valid(c, d, bss):
    bs = bss[c] - {d}
    es = bss[d] - {c}
    if not bs:
        return False
    if not es:
        return False
    if len(bs | es) < 2:
        return False    
    return True

N, M, Es = read_data()
if solve(N, M, Es):
    print("YES")
else:
    print("NO")