#include "boxes.h"
#include "bits/stdc++.h"
#define ll long long
using namespace std;
ll delivery(int N,int K,int L,int positions[]){
if(K==1){
ll ans=0;
for(int i=0;i<N;i++){
ans+=min(positions[i],L-positions[i])*2;
}
return ans;
}
if(K==N){
ll ans=1e18;
ans=min(ans,L*1LL);
ans=min(ans,(L-positions[0])*2LL);
ans=min(ans,positions[N-1]*2LL);
for(int i=0;i<N-1;i++){
ans=min(ans,positions[i]*2LL+(L-positions[i+1])*2LL);
}
return ans;
}
ll pref[N], suf[N];
for(int i=0;i<K;i++){
pref[i]=positions[i];
}
for(int i=K;i<N;i++){
pref[i]=pref[i-K]+min(positions[i-K],L-positions[i-K])+positions[i];
}
for(int i=N-1;i>=N-K;i--){
suf[i]=(L-positions[i]);
}
for(int i=N-K-1;i>=0;i--){
suf[i]=suf[i+K]+min(positions[i+K],L-positions[i+K])+(L-positions[i]);
}
ll ans=1e18;
for(int i=0;i<N-1;i++){
ans=min(ans,pref[i]+min(positions[i],L-positions[i])+suf[i+1]+min(positions[i+1],L-positions[i+1]));
}
ans=min(ans,suf[0]+min(L-positions[0],positions[0]));
ans=min(ans,pref[N-1]+min(L-positions[N-1],positions[N-1]));
return ans;
}
