题解 | #查找兄弟单词#

aline = input().split()
n = int(aline[0])
# aset = set(aline[1:-2]) # 字典若去重，则用集合（set）
dictionary = aline[1:-2]  # 字典若不去重，则用列表（list）
x = aline[-2]
k = int(aline[-1])
characters = set(x)
freq = {}
for i in characters:
    freq[i] = x.count(i)
brothers = []
for ele in dictionary:
    if ele != x and len(ele) == len(x):
        # 不考虑单词中有重复字符
        # for i in characters:
        #     if i not in ele:
        #         break
        # brothers.append(ele)

        # 考虑单词中有重复字符
        # 方法一：x的字母频次（可存为常量字典）若与ele的字母频次不同，则非兄弟单词
        for i in characters:
            if freq[i] != ele.count(i):
                break
        else:
            brothers.append(ele)

        # 方法二：ele和x分别排序成新的字符串（sorted(x)可存为常量），新字符串相等即为兄弟单词；长单词排序比较耗时
        # if sorted(ele) == sorted(x):
        #     brothers.append(ele)
brothers.sort(key=None, reverse=False)
print(len(brothers))
if k < len(brothers):
    print(brothers[k - 1])