题解 | #查找兄弟单词#

import sys
line = sys.stdin.readline().strip()
line = line.split()
n= line[0]
dic = line[1:-1]
x = line[-2]
k = int(line[-1])
ans = []
for word in dic:
    if word != x and len(word) == len(x):   
        x1 = x     #  每一次比较一个新的单词， 都需要比较完整的x
        for letter in word:
            if letter in x1:
                idx = x1.index(letter)
                x1 = x1[:idx] + x1[idx+1:]
        if x1 == '':
            ans.append(word)
ans = sorted(ans)

print(len(ans))
if len(ans) >= k:
    print(ans[k-1])