Count Pair Difference

Given N integers, count the number of pairs of integers whose difference is K.

Input Format

The first line contains N and K.
The second line contains N numbers of the set. All the N numbers are unique.

Constraints

• 2 <= N <= (10^5)
• 0 < K < (10^9)
• Each integer will be greater than 0 and at least K smaller than (2^31)-1.

Output Format

An integer that tells the number of pairs of integers whose difference is K .

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.

Solution:

n,d=[int(i) for i in input().split()]

a = [int(i) for i in input().split()]

s = set(a)

c = 0

for i in a:

    if i+d in s:

        c+=1

print(c)