#include <bits/stdc++.h>
using namespace std;
long long a[100005];
int main() {
  long long i, n, m, d, b, c1, c2;
  cin >> n >> d >> b;
  for (i = 1; i <= n; i++) {
    cin >> a[i];
    a[i] += a[i - 1];
  }
  m = (n + 1) / 2;
  c1 = c2 = 0;
  for (i = 1; i <= m; i++) c1 += (a[min(n, i * (d + 1))] - c1 * b >= b);
  for (i = n; i > m; i--)
    c2 += (n * b - a[max(0ll, n - (n + 1 - i) * (d + 1))] - c2 * b >= b);
  cout << max(m - c1, n - m - c2) << endl;
  return 0;
}
