package main

import . "fmt"

func main() {
	var n,d int
	Scan(&n,&d)
	a := make([]int, n)
	for i := range a {
		Scan(&a[i])
	}
	
	ans := 0
	
	m1 := map[int]int{}
	m2 := map[int]int{}
	
	for i := range a {
		j := len(a)-1-i
		aj := a[j]
		if c, ok := m2[aj+d]; ok {
			ans += c
		}
		if c, ok := m1[aj+d]; ok {
			m2[aj] += c
		}
		m1[aj]++
	}
	
	Println(ans)
}