#include <bits/stdc++.h>
using namespace std;
const long long maxN = 1e5 + 10;
long long n, d, k, a[maxN], sum[maxN], cnt1, cnt, b, i, ans, x;
int main() {
  scanf("%I64d%I64d%I64d", &n, &d, &b);
  for (i = 1; i <= n; i++) scanf("%I64d", &a[i]), sum[i] = sum[i - 1] + a[i];
  for (i = 1; i <= n / 2; i++) {
    x = sum[((n) < (i * d + i) ? (n) : (i * d + i))] - cnt * b;
    if (x >= b) cnt++;
    x = sum[n] - sum[((n - i * d - i) > (0) ? (n - i * d - i) : (0))] -
        cnt1 * b;
    if (x >= b) cnt1++;
  }
  ans = n / 2 - ((cnt) < (cnt1) ? (cnt) : (cnt1));
  printf("%I64d", ans);
}
