#include <bits/stdc++.h>
using namespace std;
int a[100005];
int main(void) {
  int n, x, k;
  scanf("%d %d %d", &n, &x, &k);
  for (int i = 0; i < n; i++) {
    scanf("%d", a + i);
  }
  sort(a, a + n);
  long long sum = 0;
  for (int i = 0; i < n; i++) {
    long long p = (long long)ceil(a[i] * 1.0 / x) * x;
    sum +=
        lower_bound(a, a + n, p + (long long)k * x) -
        lower_bound(a, a + n, max((long long)a[i], p + (long long)(k - 1) * x));
  }
  cout << sum << endl;
  return 0;
}
