#include <bits/stdc++.h>
using namespace std;
int rooms, speed, per;
int students[100000];
int main() {
  cin >> rooms >> speed >> per;
  for (int i = 0; i < rooms; i++) cin >> students[i];
  int left = 0;
  int tot = 0;
  int empty = (rooms + 1) / 2;
  for (int i = 0; i < (rooms + 1) / 2; i++) {
    while (left <= min((i + 1) * speed + i, rooms - 1)) {
      tot += students[left];
      left++;
    }
    if (tot >= per) {
      tot -= per;
      empty--;
    }
  }
  tot = 0;
  int right = rooms - 1;
  int empty2 = rooms / 2;
  for (int i = 0; i < rooms / 2; i++) {
    while (right >= max(0, rooms - 1 - (i + 1) * speed - i)) {
      tot += students[right];
      right--;
    }
    if (tot >= per) {
      tot -= per;
      empty2--;
    }
  }
  cout << max(empty, empty2) << endl;
}
