lostmodulus.py

import gmpy2
from Crypto.Util.number import long_to_bytes, bytes_to_long
from binascii import unhexlify

flag = open('output.txt','r').read().strip().split(' ')[1]
ciphertext = bytes_to_long(flag)
e = 3

#Fist method of getting cube root of ciphertext
gmpy2.get_context().precision = 4096
m = long_to_bytes(round(gmpy2.root(ct,e))).decode()

#second method of using the log to base10: 10 ** log(ct)/e
m2 = long_to_bytes(pow(10,gmpy2.log10(ct)/e))

print(f'{m}\n{m2}')