#include <bits/stdc++.h>
using namespace std;
long long n, d, b, i, j, k, t1, t2, x1, x2;
long long a[100005], s[100005];
int main() {
  scanf("%I64d%I64d%I64d", &n, &d, &b);
  for (i = 1; i <= n; i++) {
    scanf("%I64d", &a[i]);
    s[i] = s[i - 1] + a[i];
  }
  for (i = 1; i <= n / 2; i++) {
    x1 = s[min(n, i + d * (i))] - s[max(1ll, i - d * (i)) - 1];
    x2 = s[min(n, n - i + 1 + d * (i))] - s[max(1ll, n - i + 1 - d * (i)) - 1];
    if ((t1 + 1) * b <= x1) {
      t1++;
    }
    if ((t2 + 1) * b <= x2) {
      t2++;
    }
  }
  printf("%I64d", n / 2 - min(t1, t2));
}
