#include <bits/stdc++.h>
using namespace std;
const int MAXN = 100000 + 1000;
int n, d, b;
int a[MAXN];
int ans1 = 0, ans2 = 0;
int main() {
  ios::sync_with_stdio(false);
  cin >> n >> d >> b;
  for (int i = 1; i <= n; i++) cin >> a[i];
  int l = 1, r = n;
  for (int i = 1; i <= n / 2; i++) {
    {
      int cur = 0;
      while (cur < b && l - i <= (long long)i * d) {
        int del = min(b - cur, a[l]);
        a[l] -= del, cur += del;
        if (a[l] == 0) l++;
      }
      if (cur != b) a[l] += cur, ans1++;
    }
    {
      int cur = 0;
      while (cur < b && (n + 1 - i) - r <= (long long)i * d) {
        int del = min(b - cur, a[r]);
        a[r] -= del, cur += del;
        if (a[r] == 0) r--;
      }
      if (cur != b) a[r] += cur, ans2++;
    }
  }
  cout << max(ans1, ans2) << endl;
  return 0;
}
