from collections import defaultdict


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

c = 0
r: dict[int, list[int]] = defaultdict(list)
for i in range(N):
    r[A[i]].append(i)

for i in range(N-2):
    a2 = A[i] + D
    l2 = r[a2]
    if len(l2) == 0: continue
    a3 = a2 + D
    l3 = r[a3]
    if len(l3) == 0: continue
    for j in l2:
        c2 = 0
        for k in l3:
            if k < j:
                c2 += 1
                continue
            c += len(l3) - c2
            break

print(c)