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

cnt=0
for i in range(N):
    for j in range(i, N):
         if  A[j] - A[i] == D:
             for k in range(j, N):
                if  A[k] - A[j] == D:
                    cnt +=1
print(cnt)