import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################

n, D = na()
a = na()
from collections import defaultdict

d = defaultdict(int)
for i in range(n):
    d[a[i]] += 1
e = defaultdict(int)

ans = 0
for i in range(n):
    ans += -e[a[i] - D] * (e[a[i] + D] - d[a[i] + D])
    e[a[i]] += 1

print(ans)