#include <bits/stdc++.h>
const long long INF = 1e17, N = 2e5 + 1;
using namespace std;
int a[N], n, m, k, sum[N], t[N];
int getime(int idx) { return min(idx, n - idx + 1); }
int getlen(int l, int r) {
  if (l > r) swap(l, r);
  int tmp = (r - l) / m;
  if ((r - l) % m != 0) tmp++;
  return tmp;
}
int f(int tmp) {
  for (int i = 1; i <= n; i++) {
    sum[i] = 0;
  }
  for (int i = 1; i <= n; i++) {
    a[i] = t[i];
  }
  int idx = 1;
  for (int i = (n / 2) - tmp + 1; i <= ((n + 1) / 2) + tmp; i++) {
    while (sum[i] != k && idx <= n) {
      if (a[idx] == 0 || getlen(idx, i) > getime(i)) {
        idx++;
      } else {
        int tmp = min(k - sum[i], a[idx]);
        a[idx] -= tmp;
        sum[i] += tmp;
      }
    }
    if (sum[i] != k) {
      return 0;
    }
  }
  return 1;
}
int main() {
  cin >> n >> m >> k;
  for (int i = 1; i <= n; i++) {
    cin >> t[i];
  }
  int l = 0, r = n / 2;
  while (l != r) {
    int mid = (l + r + 1) >> 1;
    if (f(mid)) {
      l = mid;
    } else {
      r = mid - 1;
    }
  }
  cout << (n / 2) - l;
}
