n, d = [int(x) for x in input().split()]
a = [int(x) for x in input().split()]
l = {ai: 0 for ai in a}
r = {ai: 0 for ai in a}
for ai in a:
	r[ai] += 1
ans = 0
for ai in a:
	r[ai] -= 1
	ans += l.get(ai - d, 0) * r.get(ai + d, 0)
	l[ai] += 1
print(ans)