N,D = map(int,input().split())
A = list(map(int,input().split()))
from collections import Counter
LC = Counter()
RC = Counter(A[1:])

ans = 0
for i in range(N):
    ans += LC[A[i] - D] * RC[A[i] + D]
    if i+1 < N:
        RC[A[i+1]] -= 1
    LC[A[i]] += 1
print(ans)