from collections import defaultdict

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

L = defaultdict(int)
R = defaultdict(int)
for a in A:
    R[a] += 1

ans = 0
for a in A:
    R[a] -= 1
    ans += L[a-M]*R[a+M]
    L[a] += 1

print(ans)