#include "boxes.h"
#include<bits/stdc++.h>
using namespace std;
long long l[10000005];
long long r[10000005];
long long delivery(int N, int K, int L, int p[]) {
//cerr<<"work\n";
for(int i=0;i<=N+1;i++)l[i]=r[i]=0;
for(int i=1;i<=N;i++){
int prv=max(0,i-K);
l[i]=l[prv]+p[i-1]*2;
//cerr<<l[i]<<" ";
}
//cerr<<"\n";
for(int i=N;i>=1;i--){
int prv=min(N+1,i+K);
r[i]=r[prv]+(L-p[i-1])*2;
//cerr<<r[i]<<" ";
}
//cerr<<"\n";
//cerr<<"\n";
long long ans=LLONG_MAX;
for(int i=0;i<=N;i++){
ans=min(ans,l[i]+r[i+1]);
///cerr<<i<<" "<<l[i]<<" "<<r[i+1]<<"\n";
}
for(int i=0;i+K<=N;i++){
//cerr<<i<<" "<<l[i]+L+r[i+K+1]<<"\n";
ans=min(ans,l[i]+L+r[i+K+1]);
}
//cerr<<"work\n";
return ans;
}
