#include "prize.h"
#include <bits/stdc++.h>
using namespace std;
typedef vector<int> vi;
const int MX=200010;
bool up[MX];
int L[MX], R[MX], sum, n, ans;
void my_ask(int i){
static set<int> S;
if(S.find(i)!=S.end()) return;
S.insert(i);
vi now=ask(i);
L[i]=now[0], R[i]=now[1];
}
void search(int s, int e, int lc, int rc){
if(s>e) return;
int m=(s+e)/2;
for(int i=m; i<=e; i++){
my_ask(i);
if(L[i]+R[i]==0){ ans=i; return; }
if(L[i]+R[i]==sum){
if(lc<L[i]-(i-m)) search(s,m-1,lc,R[i]+i-m);
if(rc<R[i]) search(i+1,e,L[i],rc);
return;
}
}
for(int i=m; i>=s; i--){
my_ask(i);
if(L[i]+R[i]==0){ ans=i; return; }
if(L[i]+R[i]==sum){
if(lc<L[i]) search(s,i-1,lc,R[i]);
return;
}
}
}
void get(){
srand(time(NULL));
for(int i=0; i<20; i++){
int x=rand()%n; my_ask(x);
sum=max(sum, L[x]+R[x]);
}
}
int find_best(int _n){
n=_n;
get();
ans=-1;
search(0,n-1,0,0);
assert(ans>=0);
return ans;
}
