#include <bits/stdc++.h>
using namespace std;
int dx[] = {0, 0, 1, -1, 1, -1, 1, -1};
int dy[] = {1, -1, 0, 0, -1, 1, 1, -1};
long long gcd(long long first, long long second) {
  return !second ? first : gcd(second, first % second);
}
long long lcm(long long first, long long second) {
  return (first / gcd(first, second)) * second;
}
void PLAY() {
  cout << fixed << setprecision(15);
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
}
const int MAX = 6e5;
long long n, r, k;
long long archers[MAX], dist[MAX];
bool valid(long long val) {
  memset(dist, 0, sizeof dist);
  long long tmp = 0, cursum = k;
  for (int i = 1; i <= n; ++i) {
    long long cur = val - archers[i] - tmp;
    if (cur < 0) {
      tmp += dist[i];
      continue;
    }
    if (cur > cursum) return false;
    cursum -= cur;
    tmp += cur;
    long long idx = min(i + 2 * r, n);
    dist[idx] -= cur;
    tmp += dist[i];
  }
  return true;
}
int main() {
  PLAY();
  cin >> n >> r >> k;
  for (int i = 1; i <= n; i++) {
    cin >> archers[i];
    long long x = max(i - r, 1LL);
    long long y = min(i + r, n) + 1;
    dist[x] += archers[i];
    dist[y] -= archers[i];
  }
  for (int i = 1; i <= n; i++) archers[i] = archers[i - 1] + dist[i];
  long long lo = *min_element(archers + 1, archers + n + 1);
  long long hi = lo + k + 1, res = lo;
  while (lo <= hi) {
    long long mid = (lo + hi) / 2;
    if (valid(mid)) {
      res = mid;
      lo = mid + 1;
    } else
      hi = mid - 1;
  }
  cout << res << endl;
  return 0;
}
