import os
from hashlib import md5

flag = 'MUSTCTF{<REDACTED}'

head = os.urandom(10)
tail = os.urandom(10)

def check(a, b):
    if a == b:
        return False

    if not head == a[:len(head)] == b[:len(head)]:
        return False

    if not tail == a[-len(tail):] == b[-len(tail):]:
        return False

    return md5(a).digest() == md5(b).digest()


print('head:', head.hex())
print('tail:', tail.hex())

a = bytes.fromhex(input('a: '))
b = bytes.fromhex(input('b: '))

print(flag * check(a, b))