CODEFORCES 272B Dima and Sequence <简单技巧 + 类比奇偶数>

传送门：http://codeforces.com/problemset/problem/272/B

B. Dima and Sequence

time limit per test
2 seconds

memory limit per test
256 megabytes

input
standard input

output
standard output

Dima got into number sequences. Now he's got sequence a1, a2, ..., an,
consisting of n positive integers. Also, Dima has got a functionf(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.

Input

The 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.

Output

In 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 %I64dspecifier.

Examples

input

3
1 2 4

output

3

input

35 3 1

output

1

Note

In the first sample any pair (i, j) will do, so the answer is 3.

In the second sample only pair (1, 2) will do.

#include<iostream>
#include <cstdio>
#include <cstring>

using namespace std;

int r[35];
int main()
{
int N,a,p;
long long s=0;
scanf("%d",&N);
for(int i=0; i<N; i++)
{
p=0;
scanf("%d",&a);
while(a)p+=(a&1),a>>=1;
s+=r[p];
r[p]++;
}
printf("%I64d\n",s);
return 0;
}