from sympy import isprime  # pip install sympy

def isprime_logn(n):
    primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61]

    if n in primes:
        return True

    if n <= 1 or any(n % p == 0 for p in primes):
        return False

    cnt = 0
    exp = n - 1
    while exp % 2 == 0:
        cnt += 1
        exp //= 2

    for p in primes:
        x = pow(p, exp, n)
        if x in (1, n - 1):
            continue
        for _ in range(cnt - 1):
            x = x * x % n
            if x == n - 1:
                break
        else:
            return False

    return True


n = int(input('n = '))
assert n.bit_length() == 555
assert not isprime(n) and isprime_logn(n)

print('MUSTCTF{<REDACTED>}')