integers, and has a definition of what he calls k-Intersecting Numbers.
He considers a pair of integers "k-Intersecting" if the binary representation of the numbers and
differs from each other in exactly
bits.
For example, if , the pairs of integers
and
is k-intersecting because the binary representation
and
differs exactly in two bits.
Now here's the problem: are in his sequence so that
and the pair of integers
and
is k-intersecting.
Can you help
find the number of pairs that fit in these constraints?Input Specifications
The first line contains two integers and
- the number of integers has and the number of bits in which integers in a k-intersecting pair should differ.
The second line contains the sequence
, which has.
Output Specifications
Print the number of pairs so that
and the pair of integers
and
is k-intersecting.
Sample Input 1
4 1
0 3 2 1
Sample Output 1
4
Sample Input 2
6 0
200 100 100 100 200 200
Sample Output 2
6
Sample Explanation
In the first sample, there are 4 k-intersecting pairs:
,
,
,
.
In the second sample where , there are 6 k-intersecting pairs:
,
,
,
,
,
.
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