output_description: Print the maximum number of layers in a kagami mochi that can be made.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      d_1
      :
      d_N
attempt: print(len(set(input() for i in range(int(input()))))
problem_description: Statement
  
  An _X -layered kagami mochi_ (X ≥ 1) is a pile of X round mochi (rice cake)
  stacked vertically where each mochi (except the bottom one) has a smaller
  diameter than that of the mochi directly below it. For example, if you stack
  three mochi with diameters of 10, 8 and 6 centimeters from bottom to top in
  this order, you have a 3-layered kagami mochi; if you put just one mochi, you
  have a 1-layered kagami mochi.
  
  Lunlun the dachshund has N round mochi, and the diameter of the i-th mochi is
  d_i centimeters. When we make a kagami mochi using some or all of them, at
  most how many layers can our kagami mochi have?
samples: [{"input": "4\n    10\n    8\n    8\n    6", "output": "3\n    \n\nIf we stack the mochi with diameters of 10, 8 and 6 centimeters from bottom to\ntop in this order, we have a 3-layered kagami mochi, which is the maximum\nnumber of layers.\n\n* * *"}, {"input": "3\n    15\n    15\n    15", "output": "1\n    \n\nWhen all the mochi have the same diameter, we can only have a 1-layered kagami\nmochi.\n\n* * *"}, {"input": "7\n    50\n    30\n    50\n    100\n    50\n    80\n    30", "output": "4"}]