#include"highway.h"
#include<bits/stdc++.h>
#ifndef EVAL
#include"grader.cpp"
#endif
using namespace std;
vector<pair<int,int>>g[90005];
bool is[90005];
int under[90005];
long long pivot;
void dfs(int v,int p,int depth){
for(auto to:g[v])if(to.first!=p){
if(depth+1==pivot)is[to.second]=1;
under[to.second]=to.first;
dfs(to.first,v,depth+1);
}
}
void find_pair(int n,vector<int>x,vector<int>y,int a,int b){
vector<int>v(n-1,0);
pivot=ask(v)/a;
for(int i=0;i+1<n;i++){
g[x[i]].push_back({y[i],i});
g[y[i]].push_back({x[i],i});
}
dfs(0,0,0);
int l=0,r=n-2;
while(l<r){
int mid=(l+r)>>1;
vector<int>v(n-1,0);
for(int i=l;i<=mid;i++)v[i]=is[i];
if(ask(v)!=pivot*a)r=mid;
else l=mid+1;
}
answer(0,under[l]);
}
/*
5 4 1 2 0 4
0 1
0 2
1 3
1 4
*/
