#include "hack.h" #include <bits/stdc++.h> using namespace std; using ll = long long; using vi = vector<ll>; int hack(){ int l = 1, r = 1e6, ans = 1e6; while(l < r) { int mid = (l+r)/2; if((r-l) == 1) ++mid; vi v; if(l != 1) v.push_back(1); for(int i=l; i<=mid; ++i) v.push_back(i); int x = collisions(v); if(x) { ans = mid - 1; r = mid - 1; } else l = mid; } return ans; }