#define wiwihorz
#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma loop-opt(on)
#define rep(i, a, b) for(int i = a; i <= b; i ++)
#define rrep(i, a, b) for(int i = b; i >= a; i--)
#define ceil(a, b) ((a + b - 1) / (b))
#define all(x) x.begin(), x.end()
#define INF 1000000000000000000
#define MOD 1000000007
#define eps (1e-9)
using namespace std;
#define ll long long int
#define lld long double
#define pii pair<int, int>
#define random mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count())
#ifdef wiwihorz
#define print(a...) cerr << "line " << __LINE__ << ": ", kout("[" + string(#a) + "] = ", a)
void vprint(auto L, auto R) { while(L < R) cerr << *L << " \n"[next(L) == R], ++L;}
void kout() { cerr << endl; }
template<class T1, class ... T2> void kout(T1 a, T2 ... e) { cerr << a << " ", kout(e...);}
#else
#define print(...) 0
#define vprint(...) 0
#endif
#include "boxes.h"
int n, k, l;
vector<ll> pos, dp1, dp2;
void init_(int _n, int _k, int _l) {
n = _n, k = _k, l = _l;
pos.assign(n + 1, 0);
dp1.assign(n + 1, INF);
dp2.assign(n + 1, INF);
}
ll solve() {
dp1[0] = 0, dp2[0] = 0;
rep(i, 1, n) {
rep(j, 1, k) {
if(i - j >= 0) dp1[i] = min(dp1[i], dp1[i - j] + 2 * pos[i]);
if(i - j >= 0) dp2[i] = min(dp2[i], dp2[i - j] + 2 * (l - pos[n - i + 1]));
}
}
ll ans = INF;
rep(i, 0, n) rep(j, i, n) {
ll cur = dp1[i] + ceil(j - i, k) * l + dp2[n - j];
ans = min(ans, cur);
}
return ans;
}
ll delivery(int N, int K, int L, int p[]) {
init_(N, K, L);
rep(i, 0, N - 1) pos[i + 1] = p[i];
return solve();
}
