#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, z = 0;
  cin >> n >> m;
  int a[n];
  for (int i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  for (int i = 0; i < n - 1; i++)
    for (int j = i + 1; j < n; j++)
      if (a[j] - a[i] <= m) z++;
  cout << z * 2;
}
