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: num_person = int(input())
  tests_list = []
  test_score_dict = {}
  for p in range(num_person):
      num_tests = int(input())
      tests = [list(map(int, input().split())) for t in range(num_tests)]
      tests_list.append(tests)
      test_score_dict[p + 1] = 1
  for unkinds in range(num_person + 1):
      honests = num_person - unkinds
      for i in range(num_person):
          num_target_person = len(tests_list[i])
          for n in range(num_target_person):
              target_person = tests_list[i][n][0]
              target_person_test = tests_list[i][n][1]
              test_score_dict[target_person] *= target_person_test
      contra = honests - sum(test_score_dict.values())
      if honests + contra <= num_person:
          print(honests)
          exit()
  print(0)
  
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"}]