#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define FOR(i,N) for(ll i = 0; i < N; i++)
#define all(x) (x).begin(), (x).end()
// #define F first
// #define S second
#include "boxes.h"
ll delivery(int N, int K, int L, int p[]) {
// never optimal to take more than one full circle
vector<ll> dp(N+1);
ll mxL= 0, mxR = 0;
ll i = 0;
while((ll)p[i] <= L/2) {
if (i-K >= 0) dp[i] = dp[i-K] + 2ll*(ll)p[i];
else dp[i] = 2ll*(ll)p[i];
mxL = max(mxL, dp[i]);
i++;
}
i = N-1;
while((ll)p[i] > L/2) {
if (i+K < N) dp[i] = dp[i+K] + 2ll*((ll)L-(ll)p[i]);
else dp[i] = 2ll*((ll)L-(ll)p[i]);
mxR = max(mxR, dp[i]);
i--;
}
ll res = mxL + mxR;
FOR(i, N) {
if (i+K+1 <= N && p[i] <= L/2 && p[i+K] > L/2) res = min(res, L + dp[i] + dp[i+K+1]);
}
return res;
}
