#include<bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
//#define ordered_set tree<int, null_type,less<int >, rb_tree_tag,tree_order_statistics_node_update>
#define eps 1e-9
#define MOD1 998244353
#define MOD2 1000000007
#define INV_10 299473306
#define INF 1000000001
#define PI 3.14159265358979323846
using namespace std;
long long delivery(int N, int K, int L, int p[]) {
long long cost_as[N+1], cost_des[N+1];
cost_as[0]=0;
for(int i = 1; i <= N; i++)
{
int x=(i-K);
if(x<0)
x=0;
long long cu=min(2*p[i-1], L);
cost_as[i]=cost_as[x]+cu;
}
cost_des[0]=0;
for(int i = 1; i <= N; i++)
{
int x=(i-K);
if(x<0)
x=0;
long long cu=min(2*(L-p[N-i]), L);
cost_des[i]=cost_des[x]+cu;
}
long long ans=1000000000000000000LL;
for(int i = 0; i <= N; i++)
{
long long cu=cost_as[i]+cost_des[N-i];
ans=min(ans, cu);
}
return ans;
}
//size
