题解 | #合法IP#

def run(seq):
    seq = seq.split(".")
    if len(seq) != 4:
        return False
    for s in seq:
        if not s.isdigit():
            return False
        elif len(bin(int(s))[2:]) > 8:
            return False
        elif (len(s) > 1 and s[0] == '0') or (int(s) < 0):
                return False
    return True

seq = input().strip()
if run(seq):
    print('YES')
else:
    print('NO')