#include <bits/stdc++.h>
#include "boxes.h"
using namespace std;
int n, k, l;
long long solveLeft (long long lim, int p[]) {
int takenLeft = 0;
long long len = 0;
for (long long i = lim - 1; i >= 0; --i) {
if (takenLeft == 0) {
len += 2LL * p[i];
}
++takenLeft;
if (takenLeft == k) {
takenLeft = 0;
}
}
return len;
}
long long solveRight (long long lim, int p[]) {
long long len = 0;
int takenRight = 0;
for (long long i = lim; i < n; ++i) {
if (takenRight == 0) {
len += 2LL * (l - p[i]);
}
++takenRight;
if (takenRight == k) {
takenRight = 0;
}
}
return len;
}
// #define debug(x) cout << #x << " = " << x << endl
long long delivery (int N, int K, int L, int p[]) {
int mid = L >> 1;
// debug(mid);
long long half = lower_bound(p, p + N, mid) - p;
// debug(half);
n = N, k = K, l = L;
long long ret = solveLeft(half, p) + solveRight(half, p);
// debug(ret);
int taken = 0;
long long left = half - 1, right = half;
// debug(left); debug(right);
while (taken < K and (left >= 0 or right < n)) {
if (left >= 0 and right < n) {
if (L < p[left] + p[right]) {
--left;
++taken;
} else {
++right;
++taken;
}
} else if (left >= 0) {
--left;
++taken;
} else {
++right;
++taken;
}
}
// debug(left); debug(right);
ret = min(ret, L + solveLeft(left + 1, p) + solveRight(right, p));
return ret;
}
