#include <bits/stdc++.h>
using namespace std;
int n, d, b;
int sum[120001];
int main() {
  cin >> n >> d >> b;
  for (int i = 1; i <= n; i++) {
    scanf("%d", &sum[i]);
    sum[i] += sum[i - 1];
  }
  int x1 = 0, x2 = 0;
  int cur1 = 0, cur2 = 0;
  long long int len;
  for (int i = 1; i <= n / 2 + 1; i++) {
    len = 1LL * (d + 1) * i;
    if (len > n) len = n;
    if (sum[len] >= b * (cur1 + 1))
      cur1++;
    else
      x1++;
  }
  for (int i = 1; i <= n / 2; i++) {
    len = 1LL * (d + 1) * i;
    if (len > n) len = n;
    if (sum[n] - sum[n - len] >= b * (cur2 + 1))
      cur2++;
    else
      x2++;
  }
  cout << max(x1, x2) << endl;
  return 0;
}
