#include <bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(), (x).end()
#define ll long long int
#define pii pair <int, int>
#define pb push_back
#define ff first
#define ss second
const int N = 1e7+5;
ll suff[N], pref[N];
ll F(ll x, int t, ll L){
ll cur = (t ? (L-x)*2 : x*2);
return min(L, cur);
}
ll delivery(int n, int K, int L, int p[]){
for (int i = 0; i < n; i++){
if (i) pref[i] = pref[i-1];
if ((i+1)%K == 0) pref[i] += F(p[i], 0, L);
}
for (int i = n-1; i >= 0; i--){
suff[i] = suff[i+1];
if ((n-i)%K == 0) suff[i] += F(p[i], 1, L);
}
ll a = suff[0], b = pref[n-1];
if (n%K){
a += F(p[0], 1, L);
b += F(p[n-1], 0, L);
}
ll mn = min(a, b);
for (int i = 0; i < n-1; i++){
ll x = pref[i];
if ((i+1)%K) x += F(p[i], 0, L);
x += suff[i+1];
if ((n-i-1)%K) x += F(p[i+1], 1, L);
mn = min(mn, x);
}
return mn;
}
// int main ()
// {
// ios::sync_with_stdio(false);
// cin.tie(0);
// int n, k, l;
// cin >> n >> k >> l;
// int p[n];
// for (int i = 0; i < n; i++) cin >> p[i];
// cout << delivery(n, k, l, p);
// }
