Score : 200 points
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?
Input is given from Standard Input in the following format:
N d_1 : d_N
Print the maximum number of layers in a kagami mochi that can be made.
4 10 8 8 6
3
If we stack the mochi with diameters of 10, 8 and 6 centimeters from bottom to top in this order, we have a 3-layered kagami mochi, which is the maximum number of layers.
3 15 15 15
1
When all the mochi have the same diameter, we can only have a 1-layered kagami mochi.
7 50 30 50 100 50 80 30
4