#include <bits/stdc++.h> using namespace std; vector<int> ask(int i); int find_best(int n) { int l = 0, r = n; while(l!=r) { int m = (l+r)/2; auto v = ask(m); if(v[0]>0) r=m; else if (v[1]>0) l=m+1; else {l=m; r=m;} } return l; }