#include <bits/stdc++.h>
using namespace std;
void qmax(long long &x, long long y) {
  if (x < y) x = y;
}
void qmin(long long &x, long long y) {
  if (x > y) x = y;
}
inline long long read() {
  char s;
  long long k = 0, base = 1;
  while ((s = getchar()) != '-' && s != EOF && !(isdigit(s)))
    ;
  if (s == EOF) exit(0);
  if (s == '-') base = -1, s = getchar();
  while (isdigit(s)) {
    k = k * 10 + (s ^ '0');
    s = getchar();
  }
  return k * base;
}
inline void write(long long x) {
  static char cnt, num[15];
  cnt = 0;
  if (!x) {
    putchar('0');
    return;
  }
  for (; x; x /= 10) num[++cnt] = x % 10;
  for (; cnt; putchar(num[cnt--] + 48))
    ;
}
const long long maxn = 100000 + 100;
long long n, d, b, d1;
long long a[maxn];
long long s1[maxn], s2[maxn];
signed main() {
  n = read();
  d = read();
  b = read();
  d1 = n / 2 * b;
  for (long long i = 1; i <= n; i++) a[i] = read();
  for (long long i = 1; i <= n; i++) {
    s1[i] = min(a[i], d1) + s1[i - 1];
    d1 -= min(d1, a[i]);
  }
  d1 = n / 2 * b;
  for (long long i = n; i >= 1; i--) {
    s2[i] = min(a[i], d1) + s2[i + 1];
    d1 -= min(d1, a[i]);
  }
  d1 = 0;
  long long R = n / 2, r = 0, ans1 = 0, ans2 = 0;
  for (long long i = 1; i <= R; i++) {
    r += d + 1;
    r = min(n, r);
    if (d1 + b <= s1[r])
      d1 += b;
    else
      ans1++;
  }
  R = (n + 1) / 2 + 1;
  d1 = 0;
  r = 0;
  long long l = n + 1;
  for (long long i = n; i >= R; i--) {
    l -= d + 1;
    l = max(1ll, l);
    if (d1 + b <= s2[l])
      d1 += b;
    else
      ans2++;
  }
  cout << max(ans1, ans2);
  return 0;
}
