#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
int M = U.size();
bool subtask3 = M == N - 1;
for (int i = 0; i < M; i++) {
if (U[i] != i && V[i] != i + 1) {
subtask3 = 0;
}
}
ll s = ask(vector<int>(M));
if (subtask3) {
int lo = 0, hi = N - 1;
while (lo < hi) {
int mi = (lo + hi + 1) / 2;
vector<int> w(M);
fill(w.begin(), w.begin() + mi, 1);
if (ask(w) != s) {
hi = mi - 1;
} else {
lo = mi;
}
}
answer(lo, lo + s / A);
return;
}
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);
}
vector<int> dep(N), t(N);
auto dfs = [&](auto dfs, int x, int p) -> void {
for (auto [y, z] : adj[x]) {
if (y == p) {
continue;
}
t[y] = z;
dep[y] = dep[x] + 1;
dfs(dfs, y, x);
}
};
dfs(dfs, 0, -1);
vector<vector<int>> v(N);
for (int i = 0; i < N; i++) {
v[dep[i]].push_back(i);
}
int lo = 1, hi = N - 1;
while (lo < hi) {
int mi = (lo + hi) / 2;
vector<int> w(M, 1);
for (int i = 1; i <= mi; i++) {
for (int x : v[i]) {
w[t[x]] = 0;
}
}
if (ask(w) == s) {
hi = mi;
} else {
lo = mi + 1;
}
}
int d = lo; lo = 0, hi = v[d].size() - 1;
while (lo < hi) {
int mi = (lo + hi) / 2;
vector<int> w(M);
for (int i = 0; i <= mi; i++) {
w[t[v[d][i]]] = 1;
}
if (ask(w) != s) {
hi = mi;
} else {
lo = mi + 1;
}
}
int S = v[d][lo];
dep[S] = 0;
dfs(dfs, S, -1);
vector<int> q;
for (int i = 0; i < N; i++) {
if (dep[i] == s / A) {
q.push_back(i);
}
}
lo = 0, hi = q.size() - 1;
while (lo < hi) {
int mi = (lo + hi) / 2;
vector<int> w(M);
for (int i = 0; i <= mi; i++) {
w[t[q[i]]] = 1;
}
if (ask(w) != s) {
hi = mi;
} else {
lo = mi + 1;
}
}
answer(S, q[lo]);
}
