#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
int gi() {
  int x = 0, o = 1;
  char ch = getchar();
  while ((ch < '0' || ch > '9') && ch != '-') ch = getchar();
  if (ch == '-') o = -1, ch = getchar();
  while (ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = getchar();
  return x * o;
}
int n, d, b, sum[N];
int calc() {
  int s1 = 0, s2 = 0;
  for (int i = 1; i <= (n + 1) / 2; i++) {
    int f1 = sum[min(i + 1ll * d * i, (long long)n)] - s1 * b;
    int f2 = sum[n] - sum[max(0ll, n - i - 1ll * d * i)] - s2 * b;
    if (i == n - i + 1)
      s1 += f1 >= b;
    else
      s1 += f1 >= b, s2 += f2 >= b;
  }
  return min(s1 - n % 2, s2);
}
int main() {
  cin >> n >> d >> b;
  for (int i = 1; i <= n; i++) sum[i] = sum[i - 1] + gi();
  printf("%d\n", n / 2 - calc());
  return 0;
}
