#include "boxes.h"
//#pragma GCC optimize("Ofast,unroll-loops,no-stack-protector")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <bits/stdc++.h>
using namespace std;
#define debug(s) cout<< #s <<" = "<< s <<endl
#define all(v) (v).begin(), (v).end()
#define KeepUnique(v) (v).erase( unique(all(v)), v.end() )
#define MEMSET(a,val) memset(a, val, sizeof a)
#define PB push_back
#define endl '\n'
inline int myrand(int l, int r) {
int ret = rand(); ret <<= 15; ret ^= rand();
if(ret < 0) ret = -ret; ret %= (r-l+1); ret += l;
return ret;
}
template <typename F, typename S>
ostream& operator << (ostream& os, const pair< F, S>& p) {
return os<<"(" <<p.first<<", "<<p.second<<")"; }
typedef pair<int, int> ii;
template<typename T> using min_pq =
priority_queue<T, vector<T>, greater<T> >;
//int dx[] = {-1, +0, +1, +0};
//int dy[] = {+0, +1, +0, -1};
typedef long long ll;
ll *f, *g;
long long delivery(int n, int k, int L, int p[]) {
f = new ll[n], g = new ll[n];
for(int i = 0; i < n; i++) {
if(i - k < 0) f[i] = p[i];
else f[i] = p[i] + f[i - k];
}
for(int i = n - 1; i >= 0; i--) {
if(i + k > n - 1) g[i] = L - p[i];
else g[i] = L - p[i] + g[i + k];
}
ll mn = min(f[n - 1], g[0]);
for(int i = 1; i < n; i++) {
mn = min(mn, f[i - 1] + g[i]);
} mn <<= 1;
mn = min({mn, 2ll * f[n - 1] - p[n - 1] + L - p[n - 1], f[n - 1] << 1});
mn = min({mn, 2ll * g[0] - (L - p[0]) + p[0], g[0] << 1});
return mn;
}
