def codeascii(x,codage):
    x = ord(x)
    x -= 65
    x +=codage
    x = x%26
    return chr(x+65)

def decodeascii(x,codage):
    x = ord(x)
    x -= 65
    x -= codage
    x = x%26
    return chr(x+65)

def code_phrase(phrase, nbrcodage):
    text=""
    for lettre in phrase:
        text= text + str(codeascii(lettre, nbrcodage))
    return text


def decode_phrase(phrase, nbrdecode):
    text=""
    for lettre in phrase:
        text= text + str(decodeascii(lettre, nbrdecode))
    return text

def readtxt(x):
    destination = open("out.txt", "w")

    text= ""

    with open("txt.txt", "r") as fichier:
        text = fichier.read().rstrip('\n\r')

    print(text)
    text = decode_phrase(text, x)
    print(text)

    destination.write(text)

    destination.close()
    fichier.close()


readtxt(5)