#include <bits/stdc++.h>
using namespace std;
#include "prize.h"
const int LIM = 480;
int ans, val;
vector<int> q;
void search(int l, int r, int lx, int rx){
if(l > r || ans >= 0 || lx + rx == val) return;
int m1 = (l + r) / 2, m2 = m1 + 1, x, cnt = -1;
while(q[0] + q[1] < val){
if(m1-l > r-m2) x = m1--;
else x = m2++;
q = ask(x);
if(q[0] + q[1] == 0) return void(ans = x);
++cnt;
}
search(l, m1, lx, rx + cnt);
search(m2, r, lx + cnt, rx);
}
int find_best(int n){
ans = val = -1;
for(int i=0; i<min(n, LIM); ++i){
q = ask(i);
val = max(val, q[0] + q[1]);
}
search(0, n-1, 0, 0);
return ans;
}
