def check_letters_line(row):
	"""
	Check whether the input is legal and organize it.

	:param row: (str) Input letter
	:return: (bool) Check if it is a legal string
	:return: (str) Remove spaces and convert to lowercase
	"""
	new_row = row.replace(' ', '').lower()
	if new_row.isalpha() is False or len(new_row) != 4:
		return False
	else:
		return new_row