#include <bits/stdc++.h>
using namespace std;
int n;
long long a[100005], sum[100005], d, b, tmp[100005];
bool check(int mid) {
  for (int i = 1; i <= n; ++i) tmp[i] = a[i];
  int R = sum[n] - sum[n - mid], L = sum[mid];
  int k = (n + 1) / 2;
  int sr = 1;
  bool flag = 0;
  for (int i = mid + 1; i <= k; ++i) {
    L = L - b + tmp[i];
    if (L < 0) {
      L = L - tmp[i] + b;
      tmp[i] += L;
      if (sr < i) sr = i + 1;
      while (sr <= n) {
        if ((sr - i - 1) / d + 1 > i) break;
        long long delta = tmp[sr];
        tmp[sr] -= min(b - tmp[i], delta);
        tmp[i] += min(b - tmp[i], delta);
        if (tmp[i] >= b) break;
        ++sr;
      }
      if (tmp[i] < b) return false;
      L = 0;
    }
  }
  sr = n;
  for (int i = n - mid; i > k; --i) {
    R = R - b + tmp[i];
    if (R < 0) {
      R = R - tmp[i] + b;
      tmp[i] += R;
      if (sr > i) sr = i - 1;
      while (sr >= 1) {
        if ((i - sr - 1) / d + 1 > n - i + 1) break;
        long long delta = tmp[sr];
        tmp[sr] -= min(delta, b - tmp[i]);
        tmp[i] += min(delta, b - tmp[i]);
        if (tmp[i] >= b) break;
        --sr;
      }
      if (tmp[i] < b) return 0;
      R = 0;
    }
  }
  return 1;
}
void Solve() {
  scanf("%d%lld%lld", &n, &d, &b);
  for (int i = 1; i <= n; ++i) scanf("%lld", &a[i]);
  for (int i = 1; i <= n; ++i) sum[i] = sum[i - 1] + a[i];
  int l = 0, r = (n + 1) / 2;
  while (l < r) {
    int mid = (l + r) >> 1;
    if (check(mid))
      r = mid;
    else
      l = mid + 1;
  }
  printf("%d\n", l);
}
int main() { Solve(); }
