//#include "boxes.h"
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define ff(i,a,b) for(int i=a;i<=b;i++)
#define fb(i,b,a) for(int i=b;i>=a;i--)
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef pair<int,int> pii;
const int maxn = 100005;
const ll inf = 1e18 + 5;
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
// os.order_of_key(k) the number of elements in the os less than k
// *os.find_by_order(k) print the k-th smallest number in os(0-based)
int n, k, l;
int niz[maxn];
ll dp1[maxn];
ll dp2[maxn];
int pola = 0;
ll dist1(int X, int Y){
if(niz[X] <= pola && niz[Y] <= pola)return 2 * niz[Y];
if(niz[X] <= pola && niz[Y] > pola)return l;
if(niz[X] > pola && niz[Y] > pola)return 2 * (l - niz[Y]);
assert(false);
}
// X < Y
ll dist2(int X, int Y){
if(niz[X] > pola && niz[Y] > pola)return 2 * (l - niz[Y]);
if(niz[X] <= pola && niz[Y] > pola)return l;
if(niz[X] <= pola && niz[Y] <= pola)return 2 * niz[Y];
assert(false);
}
ll delivery(int N, int K, int L, int positions[]){
n = N, k = K, l = L;
ff(i,1,n)niz[i] = positions[i - 1];
ff(i,1,n)dp1[i] = dp2[i] = inf;
pola = l / 2;
dp1[0] = 0;
ff(i,1,n){
fb(j,i,max(1,i - k + 1)){
dp1[i] = min(dp1[i], dp1[j - 1] + dist1(j, i));
}
}
dp2[n + 1] = 0;
fb(i,n,1){
ff(j,i,min(n, i + k - 1)){
dp2[i] = min(dp2[i], dp2[j + 1] + dist2(i, j));
}
}
ll rez = inf;
ff(i,0,n)rez = min(rez, dp1[i] + dp2[i + 1]);
return rez;
}
//int main()
//{
// ios::sync_with_stdio(false);
// cout.tie(nullptr);
// cin.tie(nullptr);
// cin >> n >> k >> l;
// ff(i,1,n)cin >> niz[i];
//
// ff(i,1,n)dp1[i] = dp2[i] = inf;
// pola = l / 2;
//
// dp1[0] = 0;
// ff(i,1,n){
// fb(j,i,max(1,i - k + 1)){
// dp1[i] = min(dp1[i], dp1[j - 1] + dist1(j, i));
// }
// }
//
// dp2[n + 1] = 0;
// fb(i,n,1){
// ff(j,i,min(n, i + k - 1)){
// dp2[i] = min(dp2[i], dp2[j + 1] + dist2(i, j));
// }
// }
//
// ll rez = inf;
// ff(i,0,n)rez = min(rez, dp1[i] + dp2[i + 1]);
//
// cout << rez << endl;
//
// return 0;
//}
/**
3 2 8
1 2 5
// probati bojenje sahovski ili slicno
**/
