#include "books.h"
#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define rep2(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
#define rrep(i, n) for (int i = (int)(n) - 1; i >= 0; --i)
#define rrep2(i, a, b) for (int i = (int)(b) - 1; i >= (int)(a); --i)
#define all(v) begin(v), end(v)
#define rall(v) rbegin(v), rend(v)
using namespace std;
using ll = long long;
constexpr ll inf = 1e18;
template<class T, class U> bool chmin(T& a, const U& b) { return a > b ? a = b, true : false; }
template<class T, class U> bool chmax(T& a, const U& b) { return a < b ? a = b, true : false; }
long long minimum_walk(std::vector<int> p, int s) {
int n = p.size();
if (is_sorted(all(p))) return 0;
ll ans = 0;
{
while (p.back() == n - 1) {
if (s == n - 1) {
--s;
ans += 2;
}
p.pop_back();
--n;
}
reverse(all(p));
rep (i, n) p[i] = n - 1 - p[i];
s = n - 1 - s;
while (p.back() == n - 1) {
if (s == n - 1) {
--s;
ans += 2;
}
p.pop_back();
--n;
}
reverse(all(p));
rep (i, n) p[i] = n - 1 - p[i];
s = n - 1 - s;
}
rep (i, n) ans += abs(p[i] - i);
vector<int> mns(n), mxs(n);
{
vector<bool> seen(n);
rep (i, n) {
if (seen[i]) continue;
int j = i;
int mx = 0;
do {
seen[j] = true;
chmax(mx, j);
j = p[j];
} while (i != j);
j = i;
do {
mns[j] = i;
mxs[j] = mx;
j = p[j];
} while (i != j);
}
}
vector<vector<ll>> dp(n + 1, vector<ll>(n + 1, inf));
dp[mns[s]][mxs[s] + 1] = 0;
rep2 (len, 1, n + 1) {
rep (l, n + 1 - len) {
int r = l + len;
if (dp[l][r] == inf) continue;
if (l != 0) chmin(dp[mns[l - 1]][max(r, mxs[l - 1] + 1)], dp[l][r] + 1);
if (r != n) chmin(dp[min(l, mns[r])][mxs[r] + 1], dp[l][r] + 1);
}
}
return ans + dp[0][n];
}
