#include<iostream>//p1102 43分
#include<algorithm>
using namespace std;
long long b[10000010];
long long n, c, s;
int main(){
    cin >> n >> c;
	for(int i = 1; i <= n; i ++){
		cin >> b[i];
	}
	sort(b + 1, b + n + 1);
	for(int i = 1, l = 0, r = 0; i <= n; i ++){
		while(l < n && b[l] < b[i] + c)
			l ++;
		while(r < n && b[r] <= b[i] + c)
			r ++;
		s += r - l;
	}
	cout << s;
	return 0;
}