#include "highway.h"
#include "bits/stdc++.h"
using namespace std;
#define MAX_N 90004
int n;
vector <pair <int ,int>> adj[MAX_N];
vector <pair <int ,int>> edges;
vector <pair<int ,int>> nodes;
void bfs(int s ,int p){
nodes.clear();
vector <int> vis(n ,0);
vis[s] = vis[p] = 1;
queue <pair<int,int>> nxt;
for(auto e : adj[s])
if(e.first == p)
nxt.push(e);
while(!nxt.empty()){
int u = nxt.front().first ,f = nxt.front().second; nxt.pop();
nodes.push_back({u,f});
for(auto e : adj[u])
if(!vis[e.first])
nxt.push(e) ,vis[e.first] = 1;
}
}
int solve(int u ,int v ,long long dist){
bfs(u ,v);
int st = 0 ,en = nodes.size()-1 ,mid;
while(st < en){
mid = (st+en+1)>>1;
vector <int> w(n-1 ,0);
for(int i=mid; i<=en; i++)
w[nodes[i].second] = 1;
if(ask(w) != dist)
st = mid;
else
en = mid-1;
}
return nodes[st].first;
}
void find_pair(int N, std::vector<int> U, std::vector<int> V, int A, int B) {
n = N;
assert(U.size() == N-1);
for(int i=0; i<N-1; i++)
adj[U[i]].push_back({V[i] ,i}),
adj[V[i]].push_back({U[i] ,i}),
edges.push_back({U[i] ,V[i]});
long long dist = ask(vector<int>(n-1 ,0));
int st = 0 ,en = n-1 ,mid;
while(st < en){
mid = (st+en)>>1;
vector <int> w(n-1 ,0);
for(int i=st; i<=mid; i++)
w[i] = 1;
if(ask(w) != dist)
en = mid;
else
st = mid+1;
}
int s = solve(U[en] ,V[en] ,dist);
int t = solve(V[en] ,U[en] ,dist);
answer(s ,t);
}
