#include <bits/stdc++.h>
using namespace std;
long long n, c, a[200001], ans;
int main() {
	scanf("%lld%lld", &n, &c);
	for (int i = 1; i <= n; i++)
		scanf("%lld", &a[i]);
	sort(a + 1, a + n + 1);
	for (int i = 1; i <= n; i++)
		ans += upper_bound(a + 1, a + n + 1, a[i] + c)- lower_bound(a + 1, a + n + 1, a[i] + c);
	printf("%lld\n", ans);
	return 0;
}