#include "highway.h"
#include <bits/stdc++.h>
#include <string>
#include <iostream>
#include <cmath>
#include <numeric>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pi;
typedef pair<int, int> pl;
typedef pair<ld, ld> pd;
typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<vector<int>> vvi;
typedef vector<ld> vd;
typedef vector<long> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<vector<pi>> vvpi;
#define FOR(i, a, b) for (int i = a; i < (b); i++)
#define F0R(i, a) for (int i = 0; i < (a); i++)
#define FORd(i, a, b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i, a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto &a : x)
#define uid(a, b) uniform_int_distribution<int>(a, b)(rng)
#define len(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define F first
#define nl endl
#define S second
#define lb lower_bound
#define ub upper_bound
#define aint(x) x.begin(), x.end()
#define raint(x) x.rbegin(), x.rend()
#define ins insert
const int MOD = 1000000007;
ll N,M;
vvpi paths;
vi dist,parent,highway;
ll none = 0;
ll fill_with(vi ways){
vi quest(M,0);
for(int i:ways)quest[i] = 1;
int64_t val = ask(quest);
return val;
}
void dfs(int pos,int cost,int prev,int hway){
dist[pos] = cost;
parent[pos] = prev;
highway[pos] = hway;
for(auto a:paths[pos]){
if(a.F == prev)continue;
dfs(a.F,cost+1,pos,a.S);
}
}
void find_pair(int n, std::vector<int> U, std::vector<int> V, int A, int B) {
N = n;M = N-1;
paths = vvpi(N,vpi());
dist = vi(N,-1);
highway = vi(N,-1);
parent = vi(N,-1);
FOR(i,0,M){
paths[U[i]].pb({V[i],i});
paths[V[i]].pb({U[i],i});
}
dfs(0,0,-1,-1);
vi ends;
ll length = fill_with(ends)/A;
FOR(i,0,N){
if(dist[i] != length)continue;
ends.pb(i);
}
int l = 0,r = ends.size()-1;
while(l<r){
int mid = (l+r)/2;
vi temp;
FOR(i,0,mid+1){
temp.pb(highway[ends[i]]);
}
ll counter = fill_with(temp) - (length*A);
if(counter>0){
r = mid;
}else{
l = mid + 1;
}
}
// cout << ends[l] << endl;
answer(0,ends[l]);
}
