output_description: Print the maximum possible number of honest persons among the N people.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      A_1
      x_{11} y_{11}
      x_{12} y_{12}
      :
      x_{1A_1} y_{1A_1}
      A_2
      x_{21} y_{21}
      x_{22} y_{22}
      :
      x_{2A_2} y_{2A_2}
      :
      A_N
      x_{N1} y_{N1}
      x_{N2} y_{N2}
      :
      x_{NA_N} y_{NA_N}
attempt: n = int(input())
  a = []
  syogens = []
  
  for i in range(n):
      a.append(int(input()))  # 証言の個数
  
      syogen = [None] * (n)
  
      for j in range(a[-1]):
          xij, yij = map(int, input().split(" "))
          syogen[xij - 1] = yij
  
      syogens.append(syogen)
  
  # それぞれの人からみた正直者の数
  person_cnt = [None] * n
  
  for i in range(n):
      #
      cnt = 0
      # 順に証言を見ていく
      # 自分を正直と仮定
      cnt += 1
      for j, syogen in enumerate(syogens[i]):
          # 正直という評価があれば
          if syogen == 1:
              # 自分が正直なとき、正直と評価した対象の人が自分を正直と評価していたら矛盾しない
              if syogens[j][i] == 1:
                  cnt += 1
              # 自分が正直なとき、正直と評価した対象の人が自分を不親切と評価していたら矛盾する
              elif syogens[j][i] == 0:
                  cnt -= 1
  
          # 自分が不親切と評価した相手が自分を不親切と評価していても矛盾しない
          if syogen == 0:
              if syogens[j][i] == 0:
                  pass
                  # cnt += 1
  
      person_cnt[i] = cnt
  
  print(max(person_cnt))
  
problem_description: Statement
  
  There are N people numbered 1 to N. Each of them is either an _honest_ person
  whose testimonies are always correct or an _unkind_ person whose testimonies
  may be correct or not.
  
  Person i gives A_i testimonies. The j-th testimony by Person i is represented
  by two integers x_{ij} and y_{ij}. If y_{ij} = 1, the testimony says Person
  x_{ij} is honest; if y_{ij} = 0, it says Person x_{ij} is unkind.
  
  How many honest persons can be among those N people at most?
samples: [{"input": "3\n    1\n    2 1\n    1\n    1 1\n    1\n    2 0", "output": "2\n    \n\nIf Person 1 and Person 2 are honest and Person 3 is unkind, we have two honest\npersons without inconsistencies, which is the maximum possible number of\nhonest persons.\n\n* * *"}, {"input": "3\n    2\n    2 1\n    3 0\n    2\n    3 1\n    1 0\n    2\n    1 1\n    2 0", "output": "0\n    \n\nAssuming that one or more of them are honest immediately leads to a\ncontradiction.\n\n* * *"}, {"input": "2\n    1\n    2 0\n    1\n    1 0", "output": "1"}]