#include "prize.h"
#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair < int, int > pii;
typedef pair < ll, ll > pll;
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define SZ(x) (int)x.size()
#define Mp make_pair
#define endl "\n"
#define fast_io ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
const int N = 2e5 + 10;
const int LOG = 20;
const ll mod = 1e9 + 7;
const ll inf = 8e18;
int n;
vector < int > vec[N];
set < int > st[N];
inline vector < int > Ask(int pos)
{
if(!vec[pos].empty())
{
return vec[pos];
}
return vec[pos] = ask(pos);
}
int solve(int l, int r)
{
if(l > r) return -1;
int mid = (l + r) >> 1;
int s = Ask(mid)[0] + Ask(mid)[1];
if(!s) return mid;
auto it = st[s].lower_bound(mid);
int L = 0, R = 0;
if(it == st[s].begin() || Ask(mid)[0] != Ask(*prev(it))[0])
{
L = 1;
}
if(it == st[s].end() || Ask(mid)[1] != Ask(*it)[1])
{
R = 1;
}
if(Ask(mid)[0] == 0) L = 0;
if(Ask(mid)[1] == 0) R = 0;
st[s].insert(mid);
if(L)
{
int ret = solve(l, mid - 1);
if(ret != -1) return ret;
}
if(R)
{
int ret = solve(mid + 1, r);
if(ret != -1) return ret;
}
return -1;
}
int find_best(int _n)
{
n = _n;
return solve(0, n - 1);
}
