#include "books.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int N, S;
vector<int> P;
ll res = 0;
int l, r;
void trim_edges()
{
while (P[l] == l && l < N)
l++;
while (P[r] == r && r >= 0)
r--;
}
int cur = 0;
int go_right(int index)
{
for (int i = index; i < r; i++)
{
if (P[i] > cur)
swap(P[i], cur);
}
swap(cur, P[r]);
res += r - index;
index = r;
trim_edges();
return index;
}
int go_left(int index)
{
for (int i = index - 1; i > l; i--)
{
if (cur == 0 || P[i] < cur)
swap(P[i], cur);
}
swap(cur, P[l]);
res += index - l;
index = l;
trim_edges();
return index;
}
ll minimum_walk(vector<int> p_, int s_)
{
P = p_; S = s_;
N = P.size();
l = 0, r = N - 1;
trim_edges();
if (l == N) return 0;
res = l;
int index = l;
for (int t = 0; t < N && l <= r; t++)
{
if ((t&1) == 0)
index = go_right(index);
else
index = go_left(index);
/*cerr << '\n' << res << ": (" << l << ", " << r << ")\n";
for (auto p : P)
cerr << p << ' ';
cerr << '\n';*/
}
res += index;
return res;
}
