def has_prefix(sub_s, dic):
	"""
	:param sub_s: (str) A substring that is constructed by neighboring letters on a SIZExSIZE square grid
	:param dic: dict, a dictionary which stores all the data in FILE
	:return: (bool) If there is any words with prefix stored in sub_s
	"""
	for word in dic[sub_s[0]]:
		if word.startswith(sub_s):
			return True