N, D = map(int,input().split())
A = list(map(int,input().split()))

dct = [{}, {}, {}]
ans = 0

for i in range(N):
	if A[i] in dct[0]:
		dct[0][A[i]] += 1
	else:
		dct[0][A[i]] = 1

	if A[i]-D in dct[0]:
		if A[i] in dct[1]:
			dct[1][A[i]] += 1
		else:
			dct[1][A[i]] = 1

	if A[i]-D in dct[1]:
		if A[i] in dct[2]:
			dct[2][A[i]] += 1
		else:
			dct[2][A[i]] = 1
		
		if A[i]-2*D in dct[0]:
			ans += dct[1][A[i]-D]*dct[0][A[i]-2*D]

print(ans)