Pairs

Given an array of integers and a target value, determine the number of pairs of array elements that have a difference equal to the target value.

Example

k$=1$

arr$=[1,2,3,4]$

There are three values that differ by k$=1$:$2-1=1,3-2=1$ and $4-3=1.$ Return $3.$

Function Description

Complete the pairs function below.

pairs has the following parameter$($s$)$:

int k: an integer, the target difference

int arr$[$n$]$: an array of integers

Returns

int: the number of pairs that satisfy the criterion

Input Format

The first line contains two space$-$separated integers n and k$,$ the size of arr and the target value.

The second line contains n space$-$separated integers of the array arr.

Constraints

$2<=$n$<=10^5$

$0$