from collections import deque, defaultdict, Counter
from bisect import bisect_left, bisect_right
from itertools import permutations, combinations, groupby
from heapq import heappop, heappush
import math, sys
input = lambda: sys.stdin.readline().rstrip("\r\n")
def printl(li, sep=" "): print(sep.join(map(str, li)))
def yn(flag): print(Yes if flag else No)
_int = lambda x: int(x)-1
MOD = 998244353 #10**9+7
INF = 1<<60
Yes, No = "Yes", "No"

N, D = map(int, input().split())
A = list(map(int, input().split()))
CNT0 = defaultdict(int)
CNT1 = defaultdict(int)

ans = 0
for i in range(N):
    ans += CNT1[A[i]-D]
    CNT1[A[i]] += CNT0[A[i]-D]
    CNT0[A[i]] += 1
print(ans)