import sys
input = sys.stdin.readline
from collections import Counter

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

C1=Counter()
C2=Counter(A)

ANS=0
for i in range(N):
    a=A[i]
    C2[a]-=1

    ANS+=C1[a-D]*C2[a+D]

    C1[a]+=1

print(ANS)