#include "highway.h"
#include<bits/stdc++.h>
using namespace std;
#define endl "\n"
// #define int long long
typedef long long ll ;
const ll ooo = 1e14 ;
const ll oo = 2e9 ;
const double PI = acos(-1) ;
const ll M = 1e9 + 7 ;
const int N = 10000010 ;
vector<ll> g[100010] , cost;
ll a , b , p[100010];
map<pair<int,int> , int>mp;
void dis(int i){
cost[i] = 0 ;
priority_queue<pair<ll,ll>> q;
q.push({0 , i});
while(q.size()){
ll src = q.top().second , c = -q.top().first;
q.pop();
if(cost[src] < c) continue ;
// cout << src << endl;
for(auto x : g[src]){
// cout << x << ' ' << cost[x] << endl;
if(cost[x] > c + a){
p[x] = src;
cost[x] = c + a;
q.push({-cost[x] , x});
}
}
// cout << endl;
}
}
void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
int M = U.size();
a = A;b = B;
for(int i = 0 ; i < M ; ++i) {
g[V[i]].push_back(U[i]);
g[U[i]].push_back(V[i]) , mp[{U[i] , V[i]}] = i , mp[{V[i] , U[i]}] = i;
}
cost = vector<ll>(N , ooo);
dis(0);
vector<int> w(M , 0);
ll toll = ask(w);
vector<int> ans;
for(int i = 1 ; i < N; ++i) if(cost[i] == toll) ans.push_back(mp[{i , p[i]}]);
while(ans.size() - 1){
int sz = ans.size();
for(int i = 0 ; i < sz / 2 ; ++i) w[ans[i]] = 1;
ll tll = ask(w);
for(int i = 0 ; i < sz / 2 ; ++i) w[ans[i]] = 0;
if(toll == tll){
vector<int> ans1 ;
for(int i = sz / 2 ; i < sz ; ++i)
ans1.push_back(ans[i]) ;
ans = ans1;
}else{
vector<int> ans1 ;
for(int i = 0 ; i < sz / 2 ; ++i)
ans1.push_back(ans[i]) ;
ans = ans1;
}
}
int i = ans[0];
ll y = (p[U[i]] == V[i] ? U[i] : V[i]);
answer(0, y );
}
