#include "boxes.h"
#include <algorithm>
#include <deque>
#include <utility>
using namespace std;
typedef pair<long long, int> ii;
long long delivery(int N, int K, int L, int p[]) {
deque<ii> dp1, dp2;
long long dptable[N];
dp1.push_back(ii(0, -1));
dp2.push_back(ii(2 * (L - p[0]), -1));
for (int i = 0; i < N; ++i) {
while (!dp1.empty() && dp1.front().second + K < i) dp1.pop_front();
while (!dp2.empty() && dp2.front().second + K < i) dp2.pop_front();
if (i >= K) dptable[i] = L + dptable[i - K];
else dptable[i] = L;
if (!dp1.empty()) dptable[i] = min(dptable[i], dp1.front().first + 2 * p[i]);
if (!dp2.empty()) dptable[i] = min(dptable[i], dp2.front().first);
if (i != N - 1) {
while (!dp1.empty() && dp1.back().first >= dptable[i]) dp1.pop_back();
dp1.push_back(ii(dptable[i], i));
while (!dp2.empty() && dp2.back().first >= dptable[i] + 2 * (L - p[i + 1])) dp2.pop_back();
dp2.push_back(ii(dptable[i] + 2 * (L - p[i + 1]), i));
}
}
return dptable[N - 1];
}
