#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
mt19937 gen(chrono::steady_clock::now().time_since_epoch().count());
long long delivery(int N,int K,int L,int positions[]){
vector<ll> dp(N + 1, 1e18);
dp[0] = 0;
for (int i = 0; i < N; ++i){
dp[i + 1] = min(dp[i + 1], positions[i] * 2ll + dp[max(0, i - K + 1)]);
dp[i + 1] = min(dp[i + 1], L + dp[max(0, i - K + 1)]);
dp[i + 1] = min(dp[i + 1], 2ll * (L - positions[max(0, i - K + 1)]) + dp[max(0, i - K + 1)]);
}
ll ans = dp[N];
for (int i = 1; i <= K && i <= N; ++i){
ans = min(ans, 2ll * (L - positions[N - i]) + dp[N - i]);
}
return ans;
}
