#include "books.h"
#include <bits/stdc++.h>
#define vi vector<int>
#define pii pair<int,int>
#define fi first
#define se second
#define pb emplace_back
using namespace std;
int n;
vector<pii> v;
int inter(pii a,pii b){
if(a.fi > b.fi) swap(a,b);
if(b.se <= a.se) return b.se - b.fi;
if(b.fi >= a.se) return 0;
return a.se - b.fi;
}
long long minimum_walk(std::vector<int> p, int s) {
int r = p.size() - 1;
for(int i=0;i<r;i++) if(p[i] > i) v.pb(i, p[i]);
while(r > 0 && p[r] == r) r--;
int n = v.size(), ans = r;
for(int i=0;i<n;i++){
for(int j=i+1;j<n;j++){
ans += inter(v[i],v[j]);
}
}
return ans*2;
}
