#include <bits/stdc++.h>
using namespace std;
int sum[100001];
int a[100001];
long long n, d, b, i, j, k, l, S, r, ans, Ans;
int get(int l, int r) { return sum[r] - sum[l - 1]; }
int main() {
  scanf("%d%d%d", &n, &d, &b);
  for (i = 1; i <= n; i++) scanf("%d", &a[i]), sum[i] = sum[i - 1] + a[i];
  r = 0;
  S = (n + 1) / 2;
  for (i = 1; i <= S; i++) {
    if (get(i, (n < (d + 1) * i ? n : (d + 1) * i)) + r >= b)
      r += a[i] - b;
    else
      r += a[i], ans++;
    ;
  }
  r = 0;
  S = (n + 1) / 2;
  for (i = n; i >= S + 1; i--) {
    if (get((1 > i - d * (n - i + 1) ? 1 : i - d * (n - i + 1)), i) + r >= b)
      r += a[i] - b;
    else
      r += a[i], Ans++;
  }
  printf("%d\n", (ans > Ans ? ans : Ans));
}
