//
#ifndef __SIZEOF_INT128__
#define __SIZEOF_INT128__
#endif
#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include "highway.h"
using namespace std;
using namespace chrono;
using namespace __gnu_pbds;
template <typename T> using oset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define rep(i, p, k) for(int i(p); i < (k); ++i)
#define per(i, p, k) for(int i(p); i > (k); --i)
#define sz(x) (int)(x).size()
#define sc static_cast
typedef long long ll;
typedef long double ld;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef __int128_t lll;
//#define int ll
template <typename T = int> using par = std::pair <T, T>;
#define fi first
#define se second
#define test int _number_of_tests(in()); while(_number_of_tests--)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define pb emplace_back
struct Timer {
string name{""};
time_point<high_resolution_clock> end, start{high_resolution_clock::now()};
duration<float, std::milli> dur;
Timer() = default;
Timer(string nm): name(nm) {}
~Timer() {
end = high_resolution_clock::now(); dur= end - start;
cout << "@" << name << "> " << dur.count() << " ms" << '\n';
}
};
template <typename T = int> inline T in()
{
static T x;
std::cin >> x;
return x;
}
std::string yn(bool b)
{
if(b) return "YES\n";
else return "NO\n";
}
template <typename F, typename S> std::ostream& operator<<(std::ostream& out, const std::pair <F, S>& par);
template <typename T> std::ostream& operator<< (std::ostream& out, const std::vector <T>& wek)
{
for(const auto& i : wek)out << i << ' ';
return out;
}
template <typename F, typename S> std::ostream& operator<<(std::ostream& out, const std::pair <F, S>& par)
{
out << '{'<<par.first<<", "<<par.second<<"}";
return out;
}
#define show(x) cerr << #x << " = " << x << '\n';
constexpr int maxn = 90003;
vector <pair<int, int>> graf[maxn];
int odl[maxn];
bool xd[maxn];
void dfs(int w, bool x)
{
odl[w] = 1;
xd[w] = x;
for(auto [i, j]: graf[w])if(!odl[i])dfs(i, !x);
}
void find_pair(int n, vector <int> ka, vector <int> kb, int a, int b)
{
int m(sz(ka));
rep(i, 0, m){
graf[ka[i]].pb(kb[i], i);
graf[kb[i]].pb(ka[i], i);
}
dfs(0, 0);
vector <int> xdd[2];
rep(i, 0, n)xdd[xd[i]].pb(i);
vector vv = xdd[!sz(xdd[0]) || (sz(xdd[1]) && sz(xdd[1]) < sz(xdd[0]))];
ll d(ask(vector<int>(m, 0))/a);
auto pyt = [n,m](vector <bool> v){
vector <int> w(m);
rep(i, 0, n)if(v[i])for(auto [i, j]: graf[i])w[j] |= 1;
return ask(w);
};
int p(0), k(sz(vv)), s;
vector <bool> v(n);
while(k > p){
s = (p+k)/2;
rep(i, 0, n)v[i] = 0;
rep(i, 0, sz(vv))v[vv[i]] = i >= s;
if(pyt(v) == d*a)k = s;
else p = s+1;
}
int r(p-1);
vector <int> so;
queue <int> kul;
bool je(0);
rp:
rep(i, 0, n)odl[i] = 0;
so = {r};
kul.push(r);
odl[r] = 1;
while(kul.size()){
auto t(kul.front()); kul.pop();
for(auto [i, j]: graf[t])if(!odl[i]){
kul.push(i);
so.pb(i);
odl[i] = odl[t]+1;
}
}
if(je){
vector <int> s;
for(auto i: so)if(odl[i] == d+1)s.pb(i);
so = s;
}
p = 0, k = sz(so);
while(k > p){
s = (p+k)/2;
rep(i, 0, n)v[i] = 0;
rep(i, 0, sz(so))v[so[i]] = i >= s;
if(pyt(v) == d*a)k = s;
else p = s+1;
}
if(!je){
r = so[p-1];
je = 1;
goto rp;
}
answer(r, so[p-1]);
}
