#include "prize.h"
#include <bits/stdc++.h>
using namespace std;
const int maxn = 2e5 + 5;
int ans[maxn];
set<int> typ[maxn];
int rek(int l, int r)
{
if (r < l) return -1;
int m = (l + r) >> 1;
vector<int> v = ask(m);
int sum = v[0] + v[1]; ans[m] = v[0];
if (!sum) return m;
auto it = typ[sum].insert(m).first;
if (it == typ[sum].begin() || ans[*prev(it)] != ans[*it])
{
int val = rek(l, m-1);
if (val != -1) return val;
}
if (next(it) == typ[sum].end() || ans[*next(it)] != ans[*it])
{
int val = rek(m+1, r);
if (val != -1) return val;
}
return -1;
}
int find_best(int n)
{
return rek(0, n-1);
}
