#include <bits/stdc++.h>
//#include "grader.cpp"
#include "prize.h"
using namespace std;
#define ll long long
#define mk make_pair
const int N = 2e5 + 7;
vector < int > a[N];
int mx, ans = -1;
int cnt;
int period = 500;
void divide (int l, int r){
if (a[l][0] == -1)
a[l] = ask(l);
if (a[l][0] + a[l][1] == 0){
ans = l;
return;
}
if (a[r][0] == -1)
a[r] = ask(r);
if (a[r][0] + a[r][1] == 0){
ans = r;
return;
}
if (l + 1 >= r)
return;
if (a[l][0] + a[l][1] < mx){
divide(l + 1, r);
return;
}
if (a[r][0] + a[r][1] < mx){
divide(l, r - 1);
return;
}
int mid = (l + r) >> 1;
if (a[mid][0] == -1)
a[mid] = ask(mid);
if (a[mid][0] + a[mid][1] == 0){
ans = mid;
return;
}
if (a[mid][0] + a[mid][1] < mx){
divide(l, mid - 1);
divide(mid + 1, r);
return;
}
if (a[mid][1] - a[r][1])
divide(mid, r);
if (ans != -1)
return;
if (a[l][1] - a[mid][1])
divide(l, mid);
}
void calc (int l, int r){
if (a[l][0] + a[l][1] == 0){
ans = l;
return;
}
while (l < r && a[l][0] + a[l][1] < mx){
l++;
if (a[l][0] == -1)
a[l] = ask(l);
if (a[l][0] + a[l][1] == 0){
ans = l;
return;
}
}
if (a[r][0] + a[r][1] == 0){
ans = r;
return;
}
while (l < r && a[r][0] + a[r][1] < mx){
r--;
if (a[r][0] == -1)
a[r] = ask(r);
if (a[r][0] + a[r][1] == 0){
ans = r;
return;
}
}
if (l == r)
return;
if (a[l][1] - a[r][1])
divide(l, r);
}
int find_best (int n){
for (int i = 0; i < n; i++){
a[i].resize(2);
a[i][0] = a[i][1] = -1;
}
for (int i = 0; i < n; i += period){
a[i] = ask(i);
mx = max(mx, a[i][0] + a[i][1]);
if (a[i][0] + a[i][1] == 0)
return i;
}
a[n - 1] = ask(n - 1);
mx = max(mx, a[n - 1][0] + a[n - 1][1]);
if (a[n - 1][0] + a[n - 1][1] == 0)
return n - 1;
for (int i = 0; i < n; i += period){
calc(i, min(n - 1, i + period));
if (ans != -1)
break;
}
//cout << ans << endl;
return ans;
}
