/*
Code by @marlov
*/
#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
#include <vector>
#include <string>
#include <cmath>
#include <algorithm>
#include <iomanip>
#include <utility>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <stack>
#include <queue>
#include <iterator>
#include <bitset>
#include "prize.h"
using namespace std;
typedef long long ll;
typedef pair<int,int> ii;
int N;
int sN;
int mvs=0;
int result=-1;
/*
vector<int> ask(int i){
cout<<"query: "<<i<<endl;
int rlv,rrv;
cin>>rlv>>rrv;
return {rlv,rrv};
}
*/
unordered_map<int,int> lv;
unordered_map<int,int> rv;
vector<int> query(int i){
if(!(lv.count(i)==1&&rv.count(i)==1)){
vector<int> askv=ask(i);
lv[i]=askv[0];
rv[i]=askv[1];
}
if(lv[i]+rv[i]==0) result=i;
return {lv[i],rv[i]};
}
void binary_search(int l,int r){
//cout<<"seeing:"<<l<<","<<r<<endl;
if(result!=-1) return;
if(l+1>=r) return;
vector<int> lv=query(l);
vector<int> rv=query(r);
int mid=(l+r)/2;
vector<int> midv=query(mid);
while(midv[0]+midv[1]<mvs){
mid++;
midv=query(mid);
}
if(mid==r) return;
if(midv[0]-lv[0]!=0) binary_search(l,mid);
if(rv[0]-midv[0]!=0) binary_search(mid,r);
}
//method can use int[] ask(int i) which return left and right value
int find_best(int n){
int N=n;
int sN=floor(sqrt((double)N));
//loop first sqrtN value to find max dude
for(int i=0;i<N;i+=sN){
vector<int> qv=query(i);
mvs=max(mvs,qv[0]+qv[1]);
}
//loop through sqrtN
int cl=0;
int cr=sN;
vector<int> clv;
vector<int> crv;
while(cr<N){
clv=query(cl);
if(clv[0]+clv[1]<mvs){
cl++;
continue;
}
crv=query(cr);
if(cr<N&&crv[0]+crv[1]<mvs){
cr++;
continue;
}
if(crv[0]-clv[0]!=0) binary_search(cl,cr);
swap(cl,cr);
cr=cl+sN;
}
cr=N-1;
vector<int> lastV=query(cr);
while(cr>cl&&lastV[0]+lastV[1]<mvs){
cr--;
lastV=query(cr);
}
if(lastV[0]-crv[0]!=0) binary_search(cl,cr);
return result;
}
/*
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
int val=find_best(8);
cout<<"ANSWER:"<<val<<endl;
return 0;
}
*/
/* stuff you should look for
* int overflow, array bounds
* special cases (n=1,n=0?)
* do smth instead of nothing and stay organized
*/
