#!/usr/bin/env python3 # Take each number mod 37 and map it to the following character set: 0-25 is the alphabet (uppercase), 26-35 are the decimal digits, and 36 is an underscore. with open('message.txt') as file: content = file.read().strip() print("picoCTF{", end="") for n in content.split(' '): number = int(n) number %= 37 if number < 26: print(chr(number + ord('A')), end="") elif number >= 26 and number < 36: print(number - 26, end="") elif number == 36: print('_', end="") else: print() print(f"Code author seems to have forgotten a number.... {number}") exit(1) print("}")