#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define dbg(x) cerr << #x << ": " << x << "\n";
vector<int> depth;
vector<pair<ll, int>> nah;
vector<vector<int>> arr;
map<int, map<int, int>> neh;
void dfs(int node, int prev = -1){
for(int &i : arr[node]){
if(i == prev) continue;
depth[i] = depth[node] + 1;
nah.push_back({depth[i], neh[min(node, i)][max(node, i)]});
dfs(i, node);
}
}
int maxdepth(int a, int b){
if(depth[a] > depth[b]) return a;
return b;
}
void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B) {
arr.assign(N, vector<int>());
depth.assign(N, 0);
int M = U.size();
for(int i = 0; i < (int)U.size(); i++){
if(U[i] > V[i]) swap(U[i], V[i]);
neh[U[i]][V[i]] = i;
arr[U[i]].push_back(V[i]);
arr[V[i]].push_back(U[i]);
}
vector<int> vec(M, 0);
long long x = ask(vec);
dfs(0);
for(int i = 0; i < M; i++){
if(nah[i].first == x / A){
vec[nah[i].second] = 1;
if(ask(vec) != x){
answer(0, maxdepth(U[nah[i].second], V[nah[i].second]));
return;
}
}
}
}
