#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
using namespace std;
using ll = long long int;
int delivery(int N, int K, int L, int v[]){
//N is the number of teams that need their gifts
//K is the carrying capacity
//L is the number of nodes (ex. L = 8 gives us: 0,1,2,3,4,5,6,7)
//v[] is an array
vector<int> team_pos;
team_pos.push_back(-1);
for(int i = 0; i<N; i++){
team_pos.push_back(v[i]);
}
vector<ll> cw(N+5, -1);
vector<ll> ccw(N+5, -1);
cw[0] = 0;
ccw[0] = 0;
//----- ACCOUNT FOR DEFAULT FIRST
//cw[i] = minimum total distance to DELIVER FIRST i GIFTS via CW
//ccw[i] = minimum total distance to DELIVER FIRST i GITS via CCW
for(int i = 1; i<=N; i++){
cw[i] = 2*team_pos[i];
ccw[i] = 2 * (L - team_pos[N - i + 1]);
}
//------ ACCOUNT FOR CAPACITY
//cout << "ACCOUNT FOR CAPACITY\n";
for (int i = K+1; i <= N; i++){
//cout << i << " " << i-K << "\n";
cw[i] += cw[i-K];
ccw[i] += ccw[i-K];
}
//print
/*for(int i =0 ; i<cw.size(); i++){
cout << "cw[" << i << "] = " << cw[i] << "\n";
}
cout << "\n";
for(int i =0 ; i<cw.size(); i++){
cout << "ccw[" << i << "] = " << ccw[i] << "\n";
}*/
//cout << "\n";
ll no_full = 1e9 + 1;
ll yes_full = 1e9+1;
for(int i = 0; i<=N; i++){
no_full = min(no_full, cw[i] + ccw[N-i]);
//cout << i << " " << no_full << "\n";
}
//cout << "\n";
for(int i = 0 ; i+K <= N; i++){
yes_full = min(yes_full, cw[i] + L + ccw[N-(i+K)]);
//cout << i << " " << yes_full << "\n";
}
//cout << no_full << " " << yes_full << "\n";
//cout << min(no_full, yes_full) << "\n";
cout << min(no_full, yes_full);
return min(no_full, yes_full);
}
/*
int main(){
int n;
int k;
int l;
cin >> n >> k >> l;
int v[n];
for(int i = 0; i<n; i++){
int x;
cin >> x;
v[i] = x;
}
delivery(n,k,l,v);
}*/
