Pairs#10126

Pairs

1 second

128 megabytes

Very easy

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

Output

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

Examples

Example

4 3
2 5 7 10

Example 1

Note

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