N, D = map(int, input().split())
A = list(map(int, input().split()))
x = 0
for i in range(0, N-2):
	for j in range(i, N-1):
		for k in range(j, N):
			if A[j] - A[i] == D and A[k] - A[j] == D:
				x += 1
print(x)