import os
print (os.getcwd())
os.chdir("/storage/emulated/0/PY")
print (os.getcwd())

def encrypt(key, text):
    result = ""

    for c in text:
        if ord(c) == 32:
            result += " "
        else:
            result += chr(ord(c) + key)
    print (result)
    return result



def write(filename, text):
    f = open(filename, "w")
    c = f.write(text)
    print (c)
    f.close()



def read(filename):
    f = open(filename, "r")
    c = f.read()
    f.close()
    return c



def decrypt(key, text):
    result = ""

    if key.isdigit():
        key = int(key)

    else:
        print ("Key must be integer.")
        return None

    for c in text:
        if ord(c) == 32:
            result += " "
        else:
            result += chr(int(ord(c) - key))
    print (result)



write(input("Input file name to encrypt. "), encrypt(5, read("h.txt"))
#encrypt(5, read(input("Input file name to encrypt. ")))
decrypt(input("Input key number. "), read("h.txt"))