dict = {}

def AddWord(word):
	"""add a word to dictionary
	return true if sucessful add, otherwise false"""
	dict[word] = word

def DelWord(word):
	"""delete a word from dictionary"""
	"""return true if sucessful, otherwise false"""
	dict[word] = None

def CheckWord(word):
	"""check if a word is in the dictionary"""
	upper = (word[0]).upper() + word[1:]
	lower = (word[0]).lower() + word[1:]
	"""return 'word' if the word is mispelled"""
	if (dict.get(word) == None) and (dict.get(upper) == None) and (dict.get(lower) == None):
		return word
	else:
		return None

def CheckSent(sent):
	"""spell check the given sent
	return an array of mispelled word, and [] if no mispelled words"""
	for char in '0123456789,./;\'[]\\=<>?:"{}|+-_)(*&^%$#@!~':
		sent = sent.replace(char, ' ')
	res = [];
	for word in sent.split():
		if (CheckWord(word) != None):
			res.append(word)
	return res

def LoadDic(filename):
	"""add all the words in the given file to dictionary"""
	file = open(filename)
	for line in file:
		for word in line.split():
			AddWord(word)

def IsWord(word):
	"""return true if the input is a word"""
	# if it doesn't contain space, it's word
	# if it contain '~', it's not word
	if (word.replace('~', ' ') == word):
		return None
	if (word.replace(' ', '~') == word):
		return word

def IsSent(sent):
	"""return true if input is a sentence"""
	return sent

def IsFN(filename):
	"""return true if the input is a filename"""
	# the filename must end with .???
	if len(filename) <= 4:
		return None
	if (filename[-4] != '.'):
		return None

	# the file can not contain any funny symbols
	for fn in filename:
		for char in '!@#$%^&*(){}[]|<>,?':
			if (fn == char):
				return None
	return filename

def SpellCheck(target):
	"""Spellcheck the target
	target could be a word, a sentence, an essay, or a filename"""
	if IsFN(target):
		file = open(target)
		res = []
		for line in file:
			res.extend(CheckSent(line))
		return res
	else:
		return CheckSent(target)