According to the regulations of Berland's army, a reconnaissance unit should consist of exactly two soldiers. Since these two soldiers shouldn't differ much, their heights can differ by at most *d* centimeters. Captain Bob has *n* soldiers in his detachment. Their heights are *a*<sub class="lower-index">1</sub>, *a*<sub class="lower-index">2</sub>, ..., *a*<sub class="lower-index">*n*</sub> centimeters. Some soldiers are of the same height. Bob wants to know, how many ways exist to form a reconnaissance unit of two soldiers from his detachment.

Ways (1, 2) and (2, 1) should be regarded as different.
The first line contains two integers *n* and *d* (1 ≤ *n* ≤ 1000, 1 ≤ *d* ≤ 10<sup class="upper-index">9</sup>) — amount of soldiers in Bob's detachment and the maximum allowed height difference respectively. The second line contains *n* space-separated integers — heights of all the soldiers in Bob's detachment. These numbers don't exceed 10<sup class="upper-index">9</sup>.
import math
import sys

while True:
	linha = sys.stdin.readline()
	if linha == '':
		break

	linha = linha.split()
	n = int(linha[0])
	d = int(linha[1])

	numbers = sys.stdin.readline().split()


	aux = 0
	counter = 0
	for num in range(len(numbers)):
		for x in range(num + 1,len(numbers)):
			test = int(numbers[num]) - int(numbers[x])
			if(test < 0):
				test *= (-1)
			if(test <= d):
				counter += 1


	resp = counter * (counter - 1)

	print(resp)
# 1512827041433
