#ifndef EVAL
#include "grader.cpp"
#endif
#include <bits/stdc++.h>
#include "hack.h"
using namespace std;
using ll = long long;
int task1()
{
int ans = 0;
for(int i = 2; i <= 500'000; i++) {
int co = collisions({i, 2*i});
if(co) {
ans = i;
break;
}
}
return ans;
}
int task2()
{
vector<ll> v(1'000'000);
iota(v.begin(), v.end(), 1);
ll co = collisions(v);
ll m = 1'000'000;
map<ll, int> chk;
for(ll n = 2; n <= 1'000'000; n++) {
ll k = m / n;
ll q = n * k * (k-1) / 2 + k * (m % n);
if(q == co) {
return n;
}
}
assert(0);
return -1;
}
int hack()
{
return task2();
}