题解 | #合法IP#

while True:
    try:
        a = input().split('.')
        b = 0
        for i in a:
            if i.isnumeric() == True and 0 <= int(i) <= 255:
                if len(i) > 1 and i[0] == '0':
                    pass
                else:
                    b += 1
        if b == 4:
            print('YES')
        else:
            print('NO')
    except:
        break