#include <iostream>
#include <vector>
#include "highway.h"
using namespace std;
vector<vector<pair<int, int>>> cons;
vector<int> w;
void dfs(int i, int from, int d, vector<vector<pair<int, int>>>& put){
for(pair<int, int> p : cons[i]){
int c = p.first, m = p.second;
if(c == from) continue;
put[d+1].push_back({c, m});
w[m] = 1;
dfs(c, i, d+1, put);
}
}
void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
int M = U.size();
cons = vector<vector<pair<int, int>>> (N);
for(int m = 0; m < M; m++){
cons[U[m]].push_back({V[m], m});
cons[V[m]].push_back({U[m], m});
}
int dst = ask(vector<int> (M));
auto qrange = [&](int l, int r){
vector<int> w(M);
for(int i = l; i < r; i++) w[i] = 1;
return ask(w) != dst;
};
int l = 0, r = M;
while(l + 1 < r){
int m = l + (r-l)/2;
if(qrange(l, m)) r = m;
else l = m;
}
vector<vector<pair<int, int>>> side1 (N);
vector<vector<pair<int, int>>> side2 (N);
w = vector<int>(M);
dfs(U[l], V[l], 0, side1);
w = vector<int>(M);
dfs(V[l], U[l], 0, side2);
int dst2 = (ask(w)-dst)/B;
auto bs_sel = [&](vector<pair<int, int>> sel){
int l = 0, r = sel.size();
while(l + 1 < r){
int m = l + (r-l)/2;
vector<int> lw (M);
for(int set = l; set < m; set++) lw[sel[set].second] = 1;
if(ask(lw) != dst) r = m;
else l = m;
}
return sel[l].first;
};
answer(bs_sel(side1[dst-dst2]), bs_sel(side2[dst2]));
}
