#include <bits/stdc++.h>
using namespace std;
long long n,c,a[(1<<30)+1],ai,ans,maxn;

int main (){
	cin >> n >> c;
	for (int i=1;i<=n;i++){
		scanf("%d",&ai);
		a[ai]++;
		maxn=max(maxn,ai);
	}  //输入
  
	for (int i=c;i<=maxn;i++){ //i 即题中的A 
		if(a[i]!=0&&a[i-c]!=0) ans+=a[i]*a[i-c]; //计算ans
	}
  
	cout << ans; //输出
	return 0;
}