#include <bits/stdc++.h>
using namespace std;
inline void fastio() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
}
const long long inf = 2e9;
const long long UNDEF = -1;
long long n;
long long b;
long long d;
vector<long long> vec;
long long func(vector<long long> mas, long long need) {
  long long sz = (long long)mas.size();
  for (long long i = 0; i < need - sz; ++i) {
    mas.push_back(0);
  }
  sz = (long long)mas.size();
  long long ans = need;
  long long ptr = 0;
  long long sum = 0;
  for (long long i = 0; i < need; ++i) {
    long long nptr = i + (i + 1) * d;
    nptr = min(nptr, sz - 1);
    while (ptr <= nptr) {
      sum += mas[ptr];
      ptr++;
    }
    if (sum >= b) {
      sum -= b;
      ans--;
    }
  }
  return ans;
}
long long nL, nR;
long long answer = inf;
bool ok(long long M, bool print = false) {
  vector<long long> fst;
  long long sf = 0;
  long long ptr = 0;
  while (sf < M) {
    if (sf + vec[ptr] < M) {
      fst.push_back(vec[ptr]);
      sf += vec[ptr];
    } else {
      fst.push_back(M - sf);
      break;
    }
    ptr++;
  }
  vector<long long> scnd;
  long long ss = 0;
  ptr = n - 1;
  M = n * b - M;
  while (ss < M) {
    if (ss + vec[ptr] < M) {
      scnd.push_back(vec[ptr]);
      ss += vec[ptr];
    } else {
      scnd.push_back(M - ss);
      break;
    }
    ptr--;
  }
  long long f1 = func(fst, nL);
  long long f2 = func(scnd, nR);
  if (print) {
    answer = min(answer, max(f1, f2));
  }
  if (f1 >= f2) {
    return true;
  } else {
    return false;
  }
}
void solve() {
  cin >> n >> d >> b;
  vec.resize(n);
  for (long long i = 0; i < n; ++i) {
    cin >> vec[i];
  }
  nL = (n + 1) / 2;
  nR = n / 2;
  long long L = 0, R = n * b + 1;
  while (L + 1 < R) {
    long long M = (L + R) / 2;
    if (ok(M)) {
      L = M;
    } else {
      R = M;
    }
  }
  for (long long i = max(0LL, L - 10); i < min(n * b, L + 10); ++i) ok(L, true);
  cout << answer << '\n';
}
signed main() {
  fastio();
  long long T = 1;
  while (T--) {
    solve();
  }
  return 0;
}
