#include<iostream>
using namespace std;
long long int n,c,a[200005],b[100000000],sum;
int main(){
	cin >> n >> c; 
	for (long long i=1;i<=n;i++){
		cin >> a[i];
		b[a[i]]++; 
	}
	for (long long i=1;i<=n;i++){
		if(a[i]<c){
			continue;
		}
		sum += b[a[i]-c]; 
	}
	cout << sum;
	return 0;
}