#include <iostream>
#include "prize.h"
#include <algorithm>
#include <vector>
#include <set>
#include <string>
#include <queue>
#include <map>
#include <bits/stdc++.h>
#define initrand mt19937 mt_rand(time(0));
#define rand mt_rand()
//#define int long long
#define INF 10000000000000000
#define MOD 1000000007
using namespace std;
initrand;
/*vector<int> ask(int x){
cout<<"QUERY AT "<<x<<endl;
vector<int> tr = {0, 0};
cin>>tr[0]>>tr[1];
return tr;
}*/
int get(int l, int r){
return (((rand%(r-l+1))) + l);
}
signed find_best(signed n){
vector<int> v;
for(int i =1 ;i<=n;i++) v.push_back(i);
bool found = false;
map<int, int> first;
map<int, int> last;
int ans = -1;
int q = 0;
while(!found){
int tq = get(0, v.size() - 1);
signed ta = v[tq]; //we will ask this
vector<int> qq = ask(ta-1);
q++;
assert(q<=10000);
if(qq[0] == qq[1] && qq[1]==0){
ans = ta;
found = true;
continue;
}
if(first[qq[0]] != 0){
auto it = upper_bound(v.begin(), v.end(), first[qq[0]]);
auto it1 = lower_bound(v.begin(), v.end(), ta);
v.erase(it, it1);
first[qq[0]] = min(first[qq[0]], ta);
}
else first[qq[0]] = ta;
if(last[qq[1]] != 0){
auto it = lower_bound(v.begin(), v.end(), ta);
auto it1 = lower_bound(v.begin(), v.end(), last[qq[1]]);
v.erase(it, it1);
last[qq[1]] = max(last[qq[1]], ta);
}
else last[qq[1]] = ta;
auto it = lower_bound(v.begin(), v.end(), ta);
while(it!=v.end() && (*it) == ta) {
//cout << "We should be erasing " << (*it) << endl;
v.erase(it);
it = lower_bound(v.begin(), v.end(), ta);
}
/*cout<<"Remaining array: "<<endl;
for(int j: v){
cout<<j<<" ";
}
cout<<endl;*/
}
return (ans-1);
}
/*
signed main(){
signed n;
cin>>n;
int ans = find_best(n);
cout<<"Final answer: "<<ans<<endl;
}
11 12
0 1 3
0 2 4
2 3 5
3 4 4
4 5 6
0 6 3
6 7 2
6 8 5
8 9 6
8 10 7
*/
/*
3 3
0 1 1
1 2 1
*/
