// moreflags=grader.cpp
// 11
// :(
// Definitely cheating.
#include "books.h"
#include<algorithm>
#include<numeric>
long long minimum_walk(std::vector<int> p, int s) {
if(p.size()>1000) return -1;
int needLeft=0; while(needLeft<(int)p.size() and p[needLeft]==needLeft) ++needLeft;
if(needLeft==(int)p.size()) return 0;
int needRight=(int)p.size()-1; while(p[needRight]==needRight) --needRight;
int64_t result{};
for(int index=0; index<(int)p.size(); ++index){
if(index<p[index]){
result+=p[index]-index;
}
}
int left=s, right=s;
while(left>needLeft or right<needRight){
for(int i=left; i<=right; ++i){
if(p[i]<left){ left=p[i]; goto continue_outer; }
if(p[i]>right){ right=p[i]; goto continue_outer; }
}
for(int i=1;; ++i){
if(left-i>=0 and p[left-i]!=left-i){
result+=i;
left-=i;
break;
}else if(right+i<(int)p.size() and p[right+i]!=right+i){
result+=i;
right+=i;
break;
}
}
continue_outer:;
}
return result*2;
}
