题解 | 合法IP

def is_ip(s):
    if s.count('.') != 3:
        return 0
    else:
        ls = s.split('.')
        for i in ls:
            if i.isdigit():
                if 0<int(i)<=255 and i[0] != '0':
                    continue
                elif i == '0':
                    continue
                else:
                    return 0
            else:
                return 0
        return 1
while True:
    try:
        s = input()
        if is_ip(s):
            print('YES')
        else:
            print('NO')
    except:
        break