# Pairs

# Pairs

You will be given an array of integers and a target value. Determine the number of pairs of array elements that have a difference equal to a target value.

For example, given an array of [1, 2, 3, 4] and a target value of 1, we have three values meeting the condition: , , and .

**Function Description**

Complete the *pairs* function below. It must return an integer representing the number of element pairs having the required difference.

pairs has the following parameter(s):

*k*: an integer, the target difference*arr*: an array of integers

**Input Format**

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

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

**Constraints**

- each integer will be unique

**Output Format**

An integer representing the number of pairs of integers whose difference is .

**Sample Input**

```
5 2
1 5 3 4 2
```

**Sample Output**

```
3
```

**Explanation**

There are 3 pairs of integers in the set with a difference of 2: [5,3], [4,2] and [3,1] .