#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
vector<int> W;
vector<pair<int, int>> g[90000], order;
void dfs(int node, int parent = -1) {
for (pair<int, int> i : g[node]) if (i.first != parent) {
order.push_back(i);
dfs(i.first, node);
}
}
void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
int M = U.size();
if (M != N - 1) answer(0, 0);
for (int i = 0; i < N; i++) g[i].clear();
order.clear();
for (int i = 0; i < M; i++) {
g[U[i]].push_back({V[i], i});
g[V[i]].push_back({U[i], i});
}
order.push_back({0, -1});
dfs(0);
W.resize(M);
for (int i = 0; i < M; i++) W[i] = 0;
int path_len = ask(W) / A;
int l = 0, r = M - 1;
while (l != r) {
int mid = (l + r) / 2;
for (int i = 0; i <= mid; i++) W[order[i].second] = 1;
for (int i = mid + 1; i < M; i++) W[order[i].second] = 0;
int dist = ask(W);
if (dist == path_len * B) r = mid;
else l = mid + 1;
}
int T = order[l].first;
order.clear();
dfs(T);
l = 0, r = M - 1;
while (l != r) {
int mid = (l + r) / 2;
for (int i = 0; i <= mid; i++) W[order[i].second] = 1;
for (int i = mid + 1; i < M; i++) W[order[i].second] = 0;
int dist = ask(W);
if (dist == path_len * B) r = mid;
else l = mid + 1;
}
int S = order[l].first;
answer(S, T);
}
