#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
int M = U.size();
vector<vector<pair<int, int>>> adj(N);
for (int i = 0; i < M; i++) {
adj[U[i]].emplace_back(V[i], i);
adj[V[i]].emplace_back(U[i], i);
}
auto solve = [&](int r) {
vector<int> a(M);
int64_t dis = ask(a);
vector<int> P(N, -1), cand;
auto dfs = [&](auto dfs, int x, int p, int dep) -> void {
if (dis / A == dep) {
cand.push_back(x);
}
for (auto [y, z] : adj[x]) {
if (y != p) {
P[y] = z;
dfs(dfs, y, x, dep + 1);
}
}
};
dfs(dfs, r, -1, 0);
int K = cand.size();
int lo = 0, hi = K - 1;
while (lo < hi) {
int x = (lo + hi) / 2;
for (int i = lo; i <= x; i++) {
a[P[cand[i]]] = 1;
}
int64_t y = ask(a);
for (int i = lo; i <= x; i++) {
a[P[cand[i]]] = 0;
}
if (y > dis) {
hi = x;
} else {
lo = x + 1;
}
}
answer(r, cand[lo]);
};
vector<int> dep(N), P(N, -1);
auto dfs = [&](auto dfs, int x, int p) -> void {
for (auto [y, z] : adj[x]) {
if (y != p) {
P[y] = z;
dep[y] = dep[x] + 1;
dfs(dfs, y, x);
}
}
};
dfs(dfs, 0, -1);
vector<int> a(M);
int64_t dis = ask(a);
int lo = 1, hi = *max_element(dep.begin(), dep.end());
while (lo < hi) {
int x = (lo + hi + 1) / 2;
for (int i = 1; i < N; i++) {
if (dep[i] >= x) {
a[P[i]] = 1;
}
}
int64_t y = ask(a);
for (int i = 1; i < N; i++) {
if (dep[i] >= x) {
a[P[i]] = 0;
}
}
if (y > dis) {
lo = x;
} else {
hi = x - 1;
}
}
vector<int> cand;
for (int i = 0; i < N; i++) {
if (dep[i] == lo) {
cand.push_back(i);
}
}
int K = cand.size();
lo = 0, hi = K - 1;
while (lo < hi) {
int x = (lo + hi) / 2;
for (int i = lo; i <= x; i++) {
a[P[cand[i]]] = 1;
}
int64_t y = ask(a);
for (int i = lo; i <= x; i++) {
a[P[cand[i]]] = 0;
}
if (y > dis) {
hi = x;
} else {
lo = x + 1;
}
}
solve(cand[lo]);
}
