output_description: Print the maximum number of points you can gain.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      A_1 A_2 \cdots A_{3N}
attempt: ##main#######################################
  
  ## INPUT ####################################
  N = int(input())
  # A = list(map(int,list(input().split())))
  A = input()
  AA = A.replace(" ", "")
  
  ## PROCESSING ###############################
  ans = 0
  
  # for idx in range(N*3):
  # print("first:"+ AA)
  while len(AA) > 0:
      # print(AA)
      AAA = AA[0:5]
      AAAA = list(AAA)
      AAAA.sort()
  
      c = 0
      i = 0
      deletieNumFlg = 0
      while i < len(AAAA):
          CHAR1 = AAAA[i]
          c = AAA.count(CHAR1)
  
          # print("dddd1")
          # print(CHAR1)
          # print("c:" + str( c))
          # print("dddd2")
  
          if c >= 3:
              AAAA.remove(CHAR1)
              AAAA.remove(CHAR1)
              AAAA.remove(CHAR1)
              ans = ans + 1
              deletieNumFlg = 1
              i = 99
          else:
              i = i + c
  
      # print("flg:" + str(deletieNumFlg))
      # print("next(bef):" + AA)
      if deletieNumFlg == 1:
          AA = "".join(AAAA) + AA[5:]
      else:
          AA = AA[3:]
  
      # print("next(aft):" + AA)
  
  ## OUTPUT ###################################
  
  # print("++++OUTPUT++++")
  print(ans)
  
problem_description: Statement
  
  We have 3N cards arranged in a row from left to right, where each card has an
  integer between 1 and N (inclusive) written on it. The integer written on the
  i-th card from the left is A_i.
  
  You will do the following operation N-1 times:
  
    * Rearrange the five leftmost cards in any order you like, then remove the three leftmost cards. If the integers written on those three cards are all equal, you gain 1 point.
  
  After these N-1 operations, if the integers written on the remaining three
  cards are all equal, you will gain 1 additional point.
  
  Find the maximum number of points you can gain.
samples: [{"input": "2\n    1 2 1 2 2 1", "output": "2\n    \n\nLet us rearrange the five leftmost cards so that the integers written on the\nsix cards will be 2\\ 2\\ 2\\ 1\\ 1\\ 1 from left to right.\n\nThen, remove the three leftmost cards, all of which have the same integer 2,\ngaining 1 point.\n\nNow, the integers written on the remaining cards are 1\\ 1\\ 1.\n\nSince these three cards have the same integer 1, we gain 1 more point.\n\nIn this way, we can gain 2 points - which is the maximum possible.\n\n* * *"}, {"input": "3\n    1 1 2 2 3 3 3 2 1", "output": "1\n    \n\n* * *"}, {"input": "3\n    1 1 2 2 2 3 3 3 1", "output": "3"}]