#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
vector<pair<int,int>> graph[90001];
vector<int> dist(90001,0);
vector<pair<int,int>> padre(90001,{0,0});
void dfs(int now,int ante){
for(auto u:graph[now]){
if(u.first==ante){
continue;
}
padre[u.first].first=now;
padre[u.first].second=u.second;
dist[u.first]=dist[now]+1;
}
}
vector<int> aske;
void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B){
int M = U.size();
for(int i=0;i<M;i++){
graph[U[i]].push_back({V[i],i});
graph[V[i]].push_back({U[i],i});
}
dfs(0,-1);
aske.assign(M,0);
ll res=ask(aske);
ll nue=0;
for(int i=0;i<N;i++){
if(dist[i]==res/A){
aske[padre[i].second]=1;
nue=ask(aske);
if(nue!=res){
answer(0,i);
break;
}
aske[padre[i].second]=0;
}
}
}
