#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:512000000")
using namespace std;
void solve(bool);
void precalc();
clock_t start;
int main() {
  start = clock();
  int t = 1;
  cout.sync_with_stdio(0);
  cin.tie(0);
  precalc();
  cout.precision(10);
  cout << fixed;
  int testNum = 1;
  while (t--) {
    solve(true);
  }
  cout.flush();
  return 0;
}
template <typename T>
T binpow(T q, T w, T mod) {
  if (!w) return 1 % mod;
  if (w & 1) return q * 1LL * binpow(q, w - 1, mod) % mod;
  return binpow(q * 1LL * q % mod, w / 2, mod);
}
template <typename T>
T gcd(T q, T w) {
  while (w) {
    q %= w;
    swap(q, w);
  }
  return q;
}
template <typename T>
T lcm(T q, T w) {
  return q / gcd(q, w) * w;
}
template <typename T>
void make_unique(vector<T>& a) {
  sort(a.begin(), a.end());
  a.erase(unique(a.begin(), a.end()), a.end());
}
template <typename T>
void relax_min(T& cur, T val) {
  cur = min(cur, val);
}
template <typename T>
void relax_max(T& cur, T val) {
  cur = max(cur, val);
}
void precalc() {}
void solve(bool read) {
  long long n, d, b;
  cin >> n >> d >> b;
  vector<long long> a(n);
  for (long long i = 0; i < n; ++i) {
    cin >> a[i];
  }
  long long L = -1, R = (n + 1) / 2;
  while (L + 1 < R) {
    auto cur_a = a;
    long long M = (L + R) / 2;
    long long left_sum = 0, rig_sum = 0;
    long long lef_need = 0, rig_need = n - 1;
    long long lef_uk = M, rig_uk = n - 1 - M;
    long long steps = M;
    bool flag = true;
    while (lef_uk < rig_uk) {
      ++steps;
      while (lef_need <= lef_uk + steps * d && left_sum < b) {
        long long cur_add = min(cur_a[lef_need], b - left_sum);
        cur_a[lef_need] -= cur_add;
        left_sum += cur_add;
        if (cur_a[lef_need] == 0) {
          ++lef_need;
        }
      }
      while (rig_need >= rig_uk - steps * d && rig_sum < b) {
        long long cur_add = min(cur_a[rig_need], b - rig_sum);
        cur_a[rig_need] -= cur_add;
        rig_sum += cur_add;
        if (cur_a[rig_need] == 0) {
          --rig_need;
        }
      }
      if (left_sum < b || rig_sum < b) {
        flag = false;
        break;
      }
      left_sum -= b;
      rig_sum -= b;
      ++lef_uk;
      --rig_uk;
    }
    if (flag) {
      R = M;
    } else {
      L = M;
    }
  }
  cout << R << "\n";
}
