class SimpleSubstitution:
	def __init__(self):
		self.p_alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
		self.decrypting = False

	def cipher_alphabet(self, password):
		''' (str) -> str
		Retorna um alfabeto cifrado iniciado com
		o texto da palavra chave password
		'''
		c_alphabet = []
		password = password.upper()
		for ch in password:
			if ch not in c_alphabet:
				c_alphabet.append(ch)
				idx = self.p_alphabet.find(ch)
		p_alphabet = self.p_alphabet[idx:] + self.p_alphabet[:idx]
		for ch in p_alphabet:
			if ch not in c_alphabet:
				c_alphabet.append(ch)
		return ''.join(c_alphabet)

	def encrypt(self, plaintext, password):
		'''(str, str) -> str
		Retorna o texto plano cifrado com a cifra de
		substituicao com a palavra chave password
		'''
		txt = ''
		p_alphabet = self.p_alphabet
		text = plaintext.replace(' ', '').upper()
		cipher = self.cipher_alphabet(password)
		if self.decrypting:
			p_alphabet, cipher = cipher, p_alphabet
			self.decrypting = False
		for ch in text:
			txt += cipher[p_alphabet.find(ch)]
		return txt

	def decrypt(self, ciphertext,  password):
		'''(str, str) -> str
		Retorna o texto cifrado decifrado com a cifra de
		substituicao com a palavra chave password
		'''
		self.decrypting = True
		return self.encrypt(ciphertext, password)