#!/usr/bin/python def rot13(char): c = ord(char) A = ord('A') Z = ord('Z') a = ord('a') z = ord('z') if c >= A and c <= Z: char = chr((c-A+13)%(Z-A+1)+A) elif c >= a and c <= z: char = chr((c-a+13)%(z-a+1)+a) print(char, end='') with open("flag", "r") as f: flag = f.read() for char in flag: rot13(char)