#include<bits/stdc++.h>
#include "prize.h"
#define god dimasi5eks
#pragma GCC optimize("O3")
#define fi first
#define se second
#define pb push_back
#define pf push_front
// #define fisier 1
using namespace std;
typedef long long ll;
const int mod = 1000000007;
const double dancila = 3.14159265359; // PI
const double eps = 1e-9;
int ans;
map<int, pair<int, int> > m[200002];
pair<int, int> qu(int x)
{
vector<int> v = ask(x);
return {v[0], v[1]};
}
void solve(int st, int dr)
{
if(ans != -1 || st > dr)
return;
int mid = (st + dr) / 2;
pair<int, int> cur = qu(mid);
int sum = cur.fi + cur.se;
if(sum == 0)
{
ans = mid;
return;
}
auto it = m[sum].upper_bound(mid);
bool L = 1, R = 1;
if(it != m[sum].begin())
{
it--;
if(cur.se == it -> se.se)
L = 0;
it++;
}
if(it != m[sum].end())
{
if(cur.se == it -> se.se)
R = 0;
}
m[sum][mid] = cur;
if(L)
solve(st, mid - 1);
if(R)
solve(mid + 1, dr);
}
int find_best(int n)
{
ans = -1;
solve(0, n - 1);
return ans;
}
