#include "highway.h"
#include <bits/stdc++.h>
#define dbg(x) cerr << #x << ": " << x << "\n";
#define dbgv(x) cerr << #x << ": "; for(const auto &i : x) cerr << i << " "; cerr << "\n";
using namespace std;
long long dis, a;
vector<vector<pair<int, int>>> adj;
vector<int> depth;
vector<pair<int, int>> nose;
void dfs(int node, int prev){
for(const auto &x : adj[node]){
if(x.first == prev) continue;
depth[x.first] = depth[node] + 1;
if(depth[x.first] == dis / a){
nose.push_back({x.first, x.second});
}
dfs(x.first, node);
}
}
void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
adj.assign(N, vector<pair<int, int>>());
depth.assign(N, 0);
vector<int> vec(U.size(), 0);
dis = ask(vec);
a = A;
for(int i = 0; i < (int)U.size(); i++){
adj[U[i]].push_back({V[i], i});
adj[V[i]].push_back({U[i], i});
}
dfs(0, 0);
for(const auto &i : nose){
vec[i.second] = 1;
long long aux = ask(vec);
if(aux != dis){
answer(0, i.first);
return;
}
}
}
