#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define all(a) (a).begin(), (a).end()
#define replr(i, a, b) for (int i = int(a); i <= int(b); ++i)
#define reprl(i, a, b) for (int i = int(a); i >= int(b); --i)
#define rep(i, n) for (int i = 0; i < int(n); ++i)
#define mkp(a, b) make_pair(a, b)
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef vector<int> VI;
typedef vector<PII> VPI;
typedef vector<VI> VVI;
typedef vector<VVI> VVVI;
typedef vector<VPI> VVPI;
typedef pair<ll, ll> PLL;
typedef vector<ll> VL;
typedef vector<PLL> VPL;
typedef vector<VL> VVL;
typedef vector<VVL> VVVL;
typedef vector<VPL> VVPL;
template<class T> T setmax(T& a, T b) {if (a < b) return a = b; return a;}
template<class T> T setmin(T& a, T b) {if (a < b) return a; return a = b;}
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template<class T>
using indset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#include "prize.h"
VVI qr;
VI myask(int ind) {
if (qr[ind].size()) return qr[ind];
return qr[ind] = ask(ind);
}
int sum(int ind) {
return qr[ind][0] + qr[ind][1];
}
int dfs(int l, int r) {
/*cout << "NOW PROCESSING " << l+1 << " " << r+1 << endl;*/
myask(l);
if (sum(l) == 0) return l;
myask(r);
if (sum(r) == 0) return r;
if (l > r) return -1;
if (sum(l) > sum(r)) return dfs(l, r-1);
if (sum(l) < sum(r)) return dfs(l+1, r);
if (qr[l][0] == qr[r][0]) return -1;
int m = (l + r)/2;
myask(m);
if (sum(m) == 0) return m;
int ret;
ret = dfs(l, m);
if (ret != -1) return ret;
ret = dfs(m, r);
if (ret != -1) return ret;
return -1;
}
int find_best(int n) {
qr = VVI(n);
int sz = 476;
VPI ranges;
int l = 0;
int r = sz;
while (true) {
if (l >= n) break;
if (r >= n) r = n-1;
int ret = dfs(l, r);
if (ret != -1) return ret;
l = r+1;
r = l + sz;
}
return -1;
}
