B. Dima and Sequencetime limit per test2 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard outputDima got into number sequences. Now he's got sequence a1, a2, ..., an, consisting of n positive integers. Also, Dima has got a function f(x), which can be defined with the following recurrence:  f(0) = 0;  f(2·x) = f(x);  f(2·x + 1) = f(x) + 1. Dima wonders, how many pairs of indexes (i, j) (1 ≤ i < j ≤ n) are there, such that f(ai) = f(aj). Help him, count the number of such pairs. InputThe first line contains integer n (1 ≤ n ≤ 105). The second line contains n positive integers a1, a2, ..., an (1 ≤ ai ≤ 109).The numbers in the lines are separated by single spaces.OutputIn a single line print the answer to the problem.Please, don't use the %lld specifier to read or write 64-bit integers in C++. It is preferred to use the cin, cout streams or the %I64d specifier.ExamplesInput31 2 4Output3Input35 3 1Output1NoteIn the first sample any pair (i, j) will do, so the answer is 3.In the second sample only pair (1, 2) will do.
Input31 2 4
Output3
['implementation', 'math', '*1400']