def f(ip):
    if len(ip) != 4:
        return False
    else:
        for i in ip:
            if not i.isdigit():
                return False
            if int(i) < 0 or int(i) > 255 or (i[0] == '0' and len(i) > 1):
                return False
    return True

ip = input().split('.')
if f(ip):
    print('YES')
else:
    print('NO')