Szyfr Cezara 2

def cipher(string, shift):
    output = ""
    for letter in string:
        if ord(letter) >= ord('a') and ord(letter) <= ord('z'):
            code = ((ord(letter) - ord('a'))+shift)%(ord('z')-ord('a')+1) + ord('a')
            output += chr(code)
        elif ord(letter) >= ord('A') and ord(letter) <= ord('Z'):
            code = ((ord(letter) - ord('A'))+shift)%(ord('Z')-ord('A')+1) + ord('A')
            output += chr(code)
        else:
            output += letter
    return output;

def decipher(string, shift):
    return cipher(string, -shift)

def main():
    string = "Ala ma kota, sierotka ma ryzsia"
    shift = 3
    print "Tekst do zaszyfrowania: " + string
    string = cipher(string, shift)
    print "Tekst zaszyfrowany: " + string
    string = decipher(string, shift)
    print "Tekst odszyfrowany: " + string

if __name__ == "__main__":
    main()