def check_format(input_row):
	"""
	Check if the row user input is the right format.
	:param input_row:(str) The row user input.
	:return: A string store all letters.
	"""
	lst = ''
	low = input_row.lower()

	if input_row[1] and input_row[3] and input_row[5] != ' ':
		print("Illegal input")
	else:
		if len(input_row) == 7:
			lst += low[0]+low[2]+low[4]+low[6]
			return lst
		else:
			print("Illegal input")