소프티어

import sys

input = sys.stdin.readline

n, l = map(int, input().split())

str_list = [input().strip()]

answer = n

for i in range(n-1):

  new_str = input().strip()

  new_flag = False

  for s in str_list:

    for j in range(l):

      if new_str[j] == s[j] or new_str[j] == '.' or s[j] == '.':

        pass

      else:         

        break

      if j == l-1:

        new_flag = True

    if new_flag:

      answer -= 1

      break

  str_list.append(new_str)       

print(answer)

반례 있을까요? 뭐가 잘못되었는지 잘 모르겠습니다..