Pairs

Array of unique integers and a target value $k$ are given. Determine the number of pairs of array elements that have a difference equal to a target value $k$.

Input

First line contains integers $n(2\le n\le 10^5)$ and $k(0<k<10^9)$. Second line contains $n$ unique integers in the range from $0$ to $2^{31}-1$.

Output

Print the number of pairs of array integers with difference $k$.

Examples

In the sample there are two pairs of numbers with difference $3:(5,2)$ and $(10,7)$.