#include <bits/stdc++.h>
using namespace std;
using VI = vector<int>;
using VVI = vector<VI>;
using PII = pair<int, int>;
using LL = long long;
using VL = vector<LL>;
using VVL = vector<VL>;
using PLL = pair<LL, LL>;
using VS = vector<string>;
template <class S, class T>
istream& operator>>(istream& is, pair<S, T>& p) {
  return is >> p.first >> p.second;
}
template <class T>
istream& operator>>(istream& is, vector<T>& xs) {
  for (auto& x : xs) is >> x;
  return is;
}
template <class S, class T>
ostream& operator<<(ostream& os, const pair<S, T>& p) {
  return os << p.first << " " << p.second;
}
template <class T>
ostream& operator<<(ostream& os, const vector<T>& xs) {
  for (unsigned int i = 0; i < xs.size(); ++i) os << (i ? " " : "") << xs[i];
  return os;
}
template <class T>
void maxi(T& x, T y) {
  if (x < y) x = y;
}
template <class T>
void mini(T& x, T y) {
  if (x > y) x = y;
}
const double EPS = 1e-10;
const double PI = acos(-1.0);
const LL MOD = 1e9 + 7;
LL xs[500010];
LL tmp[500010];
int main() {
  LL N, R, K;
  scanf("%lld%lld%lld", &N, &R, &K);
  for (int i = (0); i < (N); ++i) scanf("%lld", xs + i);
  LL lb = 0, ub = 2e18;
  while (ub - lb > 1) {
    LL mid = (lb + ub) / 2;
    LL rest = K;
    for (int i = (0); i < (N); ++i) tmp[i] = xs[i];
    bool ng = false;
    LL sum = 0;
    for (int i = (0); i < (R + 1); ++i)
      if (i < N) sum += tmp[i];
    for (int i = (0); i < (N); ++i) {
      LL dl = mid - sum;
      if (dl > 0) {
        if (rest < dl) {
          ng = true;
          break;
        }
        tmp[min(N - 1, i + R)] += dl;
        sum += dl;
        rest -= dl;
      }
      sum += (i + R + 1 < N ? tmp[i + R + 1] : 0ll);
      sum -= (i - R >= 0 ? tmp[i - R] : 0ll);
    }
    if (ng)
      ub = mid;
    else
      lb = mid;
  }
  printf("%lld\n", lb);
  return 0;
}
