#include "highway.h"
#include<bits/stdc++.h>
using namespace std;
#define in insert
#define all(x) x.begin(),x.end()
#define pb push_back
#define eb emplace_back
#define ff first
#define ss second
// #define int long long
typedef long long ll;
typedef vector<int> vi;
typedef set<int> si;
typedef multiset<int> msi;
typedef pair<int, int> pii;
typedef vector<pii> vpii;
const int mxn = 1e5 + 10;
int id[mxn];
vector<int> l;
vector<pair<int, int>> g[mxn];
void dfs(int to, int fr, int now, int dis) {
if(now == dis) {
l.pb(to);
return;
}
for(auto it : g[to]) {
if(it.ff == fr) continue;
id[it.ff] = it.ss;
dfs(it.ff, to, now + 1, dis);
}
}
void find_pair(int n, vector<int> U, vector<int> V, int A, int B) {
int m = U.size();
for(int i = 0; i < m; i++) {
g[U[i]].eb(V[i], i);
g[V[i]].eb(U[i], i);
}
vector<int> q(m, 1);
long long tot = ask(q);
int dis = tot / B;
dfs(0, -1, 0, dis);
int L = 0, R = (int)l.size() - 1;
while(L < R) {
int M = (L + R) / 2;
for(int i = L; i <= M; i++) {
q[id[l[i]]] = 0;
}
long long tmp = ask(q);
for(int i = L; i <= M; i++) {
q[id[l[i]]] = 1;
}
if(tmp == tot) L = M + 1;
else R = M;
}
answer(0, l[R]);
}
