#include <bits/stdc++.h>
// meow meow mrrrow nyaa :3
// vivid/stasis is very cool, you should play, it's free
using namespace std;
int shortest(int i, int j, int l) {
int a = min(i, j), b = max(i, j);
return min(b - a, l - b + a);
}
int delivery(int n, int k, int l, int positions[]) {
map<int, int> a;
for (int i = 0; i < n; i++) a[positions[i]]++;
int pos = 0, res = 0, c = k;
for (pair<int, int> p : a) {
int i = p.first, v = p.second;
int can_change = min(c, v);
if (can_change) {
v -= can_change;
c -= can_change;
res += shortest(pos, i, l);
pos = i;
}
if (v) {
int times = (v + k - 1) / k;
v -= k * times;
c -= v;
res += 2 * times * shortest(0, i, l) - shortest(0, i, l) + shortest(0, pos, l);
pos = i;
}
}
res += shortest(pos, 0, l);
return res;
}
