#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long n, m, l = 0, p = 0, i, flag = 0, k, j, r = 0, q = 0, t, curr = 0, d,
                  x;
  cin >> n >> x >> k;
  long long a[n];
  for (long long i = 0; i < n; i++) {
    cin >> a[i];
  }
  sort(a, a + n);
  for (long long i = 0; i < n; i++) {
    long long r1 = a[i] + (x * k);
    if (a[i] % x == 0) {
      r1--;
    }
    r1 -= r1 % x;
    long long r2 = r1 + x - 1;
    r1 = max(a[i], r1);
    auto it = upper_bound(a, a + n, r2);
    auto it1 = lower_bound(a, a + n, r1);
    p += it - it1;
  }
  cout << p;
  return 0;
}
