def CaesarEncrypt(plainText, shiftAmount):
    cipherText = ''
    for ch in plainText:
        cipherText = cipherText + CaesarEncryptOneCharacter(ch,shiftAmount)
    return cipherText

def CaesarEncryptOneCharacter(ch, shiftAmount):
    if ch.isalpha():
        if ch.islower():
            start= ord ('a')
        else:
            start= ord ('A') 
        letterInUnicode = ord (ch)
        letterInAlphabet = letterInUnicode - start
        shiftedLetterInAlphabet= (letterInAlphabet + shiftAmount)%26
        shiftedLetterInUnicode = shiftedLetterInAlphabet + start
        return chr(shiftedLetterInUnicode)
    else:
        return ch