#include "books.h"
#include<bits/stdc++.h>
using namespace std;
int nr, N, BG, p[1000009], d[1000009];
set < int > S;
vector < int > v[1000009];
void add (int node, int newD)
{
if (d[node] != -1) return ;
d[node] = newD, v[newD].push_back (node), S.erase (node);
int l = node, r = p[node];
if (l > r) swap (l, r);
while (1)
{
auto it = S.lower_bound (l);
if (it == S.end () || *it > r) break;
add (*it, newD);
}
}
long long minimum_walk (vector < int > pp, int ss)
{
N = pp.size (), BG = ss + 1;
for (int i=1; i<=N; i++)
p[i] = pp[i - 1] + 1;
long long ans = 0;
int lft = 0, rgt = 0;
for (int i=1; i<=N; i++)
{
int curr = i - p[i];
if (curr < 0) curr = -curr;
ans += curr;
if (i != p[i])
{
if (lft == 0) lft = i;
rgt = i;
}
}
if (lft == 0) return ans;
for (int i=1; i<=N; i++)
S.insert (i), d[i] = -1;
add (BG, 0);
for (int i=0; !v[i].empty (); i++)
for (auto it : v[i])
{
if (it > 1) add (it - 1, i + 1);
if (it < N) add (it + 1, i + 1);
}
int maxi = 0;
for (int i=lft; i<=rgt; i++)
maxi = max (maxi, d[i]);
ans += 2LL * maxi;
return ans;
}
