import string
from collections import Counter
try:
    with open('cipher.txt') as file:
        data = file.read()
        alphabet = set(string.ascii_uppercase)
except FileNotFoundError:
    print('Error')
counts = Counter(data)
dictionary = {}
keys = data[0:26]
counter = 0
itera=iter(dictionary)
for key, count in counts.most_common():
    if key in alphabet:
        dictionary[key] = keys[counter]
        counter += 1
message = ""
for letters in data:
    try:
        message += dictionary[letters]
    except KeyError:
        message += letters
        continue
print(message)