while True: try: line = str(input()).split(" ") num_word = int(line[0]) word_list=[] for i in range(num_word): word_list.append(line[i+1]) word_search = line[-2] kth = int(line[-1]) brother_list=[] length = len(word_search) #搜索单词的长度 for word in word_list: if len(word) == length and word != word_search: check = True for character in word: if word.count(character)!= word_search.count(character): check = False break if check == True: brother_list.append(word) brother_list.sort() print(len(brother_list)) if kth <=len(brother_list): print(brother_list[kth-1]) except: break