CF554B Ohana Cleans Up

Ohana Matsumae is trying to clean a room, which is divided up into an $ n $ by $ n $ grid of squares. Each square is initially either clean or dirty. Ohana can sweep her broom over columns of the grid. Her broom is very strange: if she sweeps over a clean square, it will become dirty, and if she sweeps over a dirty square, it will become clean. She wants to sweep some columns of the room to maximize the number of rows that are completely clean. It is not allowed to sweep over the part of the column, Ohana can only sweep the whole column. Return the maximum number of rows that she can make completely clean.

The first line of input will be a single integer $ n $ ( $ 1

The output should be a single line containing an integer equal to a maximum possible number of rows that are completely clean.

In the first sample, Ohana can sweep the 1st and 3rd columns. This will make the 1st and 4th row be completely clean. In the second sample, everything is already clean, so Ohana doesn't need to do anything.