output_description: Print the maximum number of times we can do the operation.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      x_1 y_1
      :
      x_N y_N
attempt: N = int(input())
  xs = {}
  ys = {}
  for i in range(N):
      pair = tuple(map(int, input().split()))
      if pair[0] not in xs:
          xs[pair[0]] = []
      xs[pair[0]].append(pair)
      if pair[1] not in ys:
          ys[pair[1]] = []
      ys[pair[1]].append(pair)
  # print(xs)
  # print(ys)
  
  newy = set()
  sumix = set()
  sumiy = set()
  sumi = set()
  for k in xs:
      if len(xs[k]) > 1:
          for pair in xs[k]:
              newy.add(pair[1])
              sumiy.add(pair[1])
              sumi.add(pair)
          sumiy.add(k)
  newx = set()
  while True:
      for y in newy:
          for pair in ys[y]:
              if pair[0] not in sumix:
                  newx.add(pair[0])
                  sumix.add(pair[0])
                  sumi.add(pair)
      # print(newx)
      newy = set()
      for x in newx:
          for pair in xs[x]:
              if pair[1] not in sumiy:
                  newy.add(pair[1])
                  sumiy.add(pair[1])
                  sumi.add(pair)
      if newy == set():
          break
  
  
  for k in ys:
      if len(ys[k]) > 1:
          for pair in ys[k]:
              newx.add(pair[0])
              sumix.add(pair[0])
              sumi.add(pair)
          sumix.add(k)
  newy = set()
  while True:
      for x in newx:
          for pair in xs[x]:
              if pair[1] not in sumiy:
                  newy.add(pair[1])
                  sumiy.add(pair[1])
                  sumi.add(pair)
      # print(newx)
      newx = set()
      for y in newy:
          for pair in ys[y]:
              if pair[0] not in sumix:
                  newx.add(pair[0])
                  sumix.add(pair[0])
                  sumi.add(pair)
      if newx == set():
          break
  
  
  if sumi == set():
      print(0)
      exit()
  ssx = sorted(sumix)
  xran = len(ssx)
  ssy = sorted(sumiy)
  yran = len(ssy)
  print(xran * yran - len(sumi))
  
problem_description: Statement
  
  There are N dots in a two-dimensional plane. The coordinates of the i-th dot
  are (x_i, y_i).
  
  We will repeat the following operation as long as possible:
  
    * Choose four integers a, b, c, d (a \neq c, b \neq d) such that there are dots at exactly three of the positions (a, b), (a, d), (c, b) and (c, d), and add a dot at the remaining position.
  
  We can prove that we can only do this operation a finite number of times. Find
  the maximum number of times we can do the operation.
samples: [{"input": "3\n    1 1\n    5 1\n    5 5", "output": "1\n    \n\nBy choosing a = 1, b = 1, c = 5, d = 5, we can add a dot at (1, 5). We cannot\ndo the operation any more, so the maximum number of operations is 1.\n\n* * *"}, {"input": "2\n    10 10\n    20 20", "output": "0\n    \n\nThere are only two dots, so we cannot do the operation at all.\n\n* * *"}, {"input": "9\n    1 1\n    2 1\n    3 1\n    4 1\n    5 1\n    1 2\n    1 3\n    1 4\n    1 5", "output": "16\n    \n\nWe can do the operation for all choices of the form a = 1, b = 1, c = i, d = j\n(2 \\leq i,j \\leq 5), and no more. Thus, the maximum number of operations is\n16."}]