#include <bits/stdc++.h>
using namespace std;
struct max_sum_set
{
vector<int64_t> values;
void insert(int64_t x)
{
values.push_back(x);
}
void erase(int64_t x)
{
values.erase(find(values.begin(), values.end(), x));
}
int64_t get(size_t k)
{
k = min(k, values.size());
nth_element(values.begin(), values.begin() + k, values.end(), greater<int64_t>{});
return accumulate(values.begin(), values.begin() + k, int64_t(0));
}
};
void divida_et_impera(
size_t d1, size_t d2, size_t p1, size_t p2,
vector<int64_t>& result, max_sum_set& V, const vector<int>& A, int mv)
{
if(d1 >= d2)
return;
size_t d = (d1 + d2) / 2, p = p1;
int64_t& r = result[d];
for(size_t i = p1; i < p2 and mv*i <= d; i++)
{
auto v = V.get(d-mv*i);
if(v > r)
r = v, p = i;
V.insert(A[i]);
}
for(size_t i = p1; i < p2 and mv*i <= d; i++)
V.erase(A[i]);
divida_et_impera(d1, d, p1, p+1, result, V, A, mv);
for(size_t i = p1; i < p; i++) V.insert(A[i]);
divida_et_impera(d+1, d2, p, p2, result, V, A, mv);
for(size_t i = p1; i < p; i++) V.erase(A[i]);
}
vector<int64_t> best_values(vector<int> A, size_t d, int mv = 1)
{
A.push_back(0);
vector<int64_t> result(d+1);
max_sum_set V;
divida_et_impera(0, d+1, 0, A.size(), result, V, A, mv);
return result;
}
int64_t solve_right(const vector<int>& A, size_t s, size_t d)
{
auto R = best_values(vector<int>(A.begin() + s, A.end()), d),
L = best_values(vector<int>(A.rbegin() + (A.size()-s), A.rend()), d, 2);
int64_t result = 0;
for(size_t r = 0; r <= d; r++)
result = max(result, R[r] + L[d-r]);
return result;
}
long long int findMaxAttraction(int n, int start, int d, int a[])
{
vector<int> A(a, a + n);
int64_t result = solve_right(A, start, d+1);
reverse(A.begin(), A.end());
result = max(result, solve_right(A, n-1 - start, d+1));
return result;
}
#ifdef XHOVA
int main()
{
int a[] = {10, 2, 20, 30, 1};
cout << findMaxAttraction(5, 2, 7, a);
}
#endif
