#include <bits/stdc++.h>
#include "highway.h"
using namespace std;
#define all(x) x.begin(), x.end()
#define pb push_back
#define ln '\n'
//#define int long long
template <class _T>
bool chmin(_T &x, const _T &y){
bool flag = false;
if ( x > y ){
x = y; flag |= true;
}
return flag;
}
template <class _T>
bool chmax(_T &x, const _T &y){
bool flag = false;
if ( x < y ){
x = y; flag |= true;
}
return flag;
}
void find_pair(int n, vector<int> U, vector<int> V, int A, int B) {
int m = (int)U.size();
assert(m == n - 1);
vector <pair<int,int>> g[n], edge(m);
vector <int> tree;
for ( int i = 0; i < m; i++ ){
g[U[i]].pb({V[i], i});
g[V[i]].pb({U[i], i});
}
function <void(int,int)> dfs = [&](int x, int par){
for ( auto [to, id]: g[x] ){
if ( to == par ){
continue;
} tree.pb(id);
edge[id] = {x, to};
dfs(to, x);
}
};
auto dis = ask(vector <int> (m, 0)) / A * B;
auto get = [&](int root){
tree.clear();
dfs(root, -1);
int l = 0, r = m - 1;
while ( l < r ){
int md = (l + r) >> 1;
vector <int> f(m, 0);
for ( int i = 0; i <= md; i++ ){
f[tree[i]] = 1;
}
if ( ask(f) == dis ) r = md;
else l = md + 1;
}
return edge[tree[l]].second;
};
int s = get(0), t = get(s);
answer(s, t);
}
