---

n = int(input())
t = int(input())

a = [int(input()) for _ in range(n)]
a.sort()

ans = 0
left = 0
right = 0

for i in range(n):
    while a[i] - a[left] > t:
        left += 1

    while right < n and a[right] - a[i] <= t:
        right += 1

    close = right - left - 1
    far = n - (right - left)

    ans += close * far

print(ans)