#ifdef EVAL
#include "boxes.h"
#endif // EVAL
#include <bits/stdc++.h>
using namespace std;
const int MaxN = 1e7;
const long long inf = 1e18;
int pos[MaxN], n, k, len;
long long dp[MaxN];
int cost(int le, int ri){
if (pos[ri] <= len / 2) return pos[ri] * 2;
if (pos[le] > len / 2) return (len - pos[le]) * 2;
return len;
}
long long delivery(int N, int K, int L, int position[]){
n = N, k = K, len = L;
for (int i = 0; i < n; ++ i)
pos[i] = position[i];
for (int i = 0; i < n; ++ i){
dp[i] = inf;
for (int j = max(0, i - k + 1); j <= i; ++ j){
long long tmp = 0;
if (j) tmp = dp[j - 1];
dp[i] = min(dp[i], tmp + cost(j, i));
}
}
return dp[n - 1];
}
#ifndef EVAL
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> n >> k >> len;
for (int i = 0; i < n; ++ i)
cin >> pos[i];
cout << delivery(n, k, len, pos);
}
/*
10 1 5
0 0 0 0 0 1 3 3 3 4
*/
#endif // EVAL
