#include <cassert>
#include <iostream>
#include <vector>
using namespace std;
const int N = 2e5 + 2;
vector<int> cache[N];
vector<int> lv(1, 1);
int sumUpper = 0;
vector<int> ask(int i);
int countQuery = 0;
vector<int> Ask(int i)
{
assert(++countQuery <= 6000);
return ask(i);
}
inline bool Type(int i) { return cache[i][0] + cache[i][1] == sumUpper; }
int Solve(int l, int r, int cntL, int cntR)
{
int cur = sumUpper - cntL - cntR;
if (l > r || cur == 0) return -1;
int i = (l + r) / 2;
while (true)
{
if (cache[i].empty()) cache[i] = Ask(i);
if (cache[i][0] + cache[i][1] == 0) return i;
if (Type(i))
return max(Solve(l, i - 1, cntL, cache[i][1]), Solve(i + 1, r, cache[i][0], cntR));
if (i == r) return Solve(l, (l + r) / 2 - 1, cntL, cntR + r - (l + r) / 2 + 1);
++i;
}
return -1;
}
int find_best(int n)
{
for (int i = 1, sum = 1; ; ++i)
{
int nex = lv.back() * lv.back() + 1;
if (sum + nex + (long long) nex * nex + 1 <= n)
{
lv.push_back(nex);
sum += nex * nex;
}
else
{
int &cur = lv.back();
while (sum + 1 + (cur + 1) * (cur + 1) + 1 <= n) ++cur;
break;
}
}
int upp = 1;
for (int i = 0; i < (int) lv.size(); ++i)
upp += lv[i];
for (int i = 0; i < n; ++i)
if ((i + 1) % (n / upp) == 0)
{
cache[i] = Ask(i);
sumUpper = max(sumUpper, cache[i][0] + cache[i][1]);
}
int last = -1, sumL = 0;
for (int i = 0, need = 0; i < n; ++i)
{
if (!cache[i].empty() && cache[i][0] + cache[i][1] == 0) return i;
need += (i + 1) % (n / upp) == 0;
need -= !cache[i].empty() && Type(i);
if (need && cache[i].empty())
{
cache[i] = Ask(i);
--need;
}
if (!cache[i].empty() && Type(i))
{
int solved = Solve(last + 1, i - 1, sumL, cache[i][1]);
if (solved != -1) return solved;
last = i;
sumL = cache[i][0];
}
}
return Solve(last + 1, n - 1, sumL, 0);
}
