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

c = 0
for i in range(N-2):
    for j in range(i + 1, N-1):
        if A[j] != A[i] + D: continue
        for k in range(j + 1, N):
            if A[k] != A[i] + D * 2: continue
            c += 1

print(c)