#include "highway.h"
//#include "grader.cpp"
#include <vector>
#include <map>
#include <utility>
#include <iostream>
#include <unordered_map>
#define ll long long
using namespace std;
const int maxn = (int)1e5 + 7;
int h[maxn];
vector < int > gr[maxn];
vector < int > vec[maxn];
vector < int > w;
map < pair < int, int >, int > mp;
int p[maxn], idc[maxn];
void dfs(int v, int pr) {
vec[h[v]].push_back(v);
p[v] = pr;
for (int to : gr[v]) {
if (to == pr) continue;
h[to] = h[v] + 1;
w[mp[{v, to}]] = 1;
idc[to] = w[mp[{v, to}]];
dfs(to, v);
}
}
void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
int m = U.size();
ll dist = 0;
w.resize(m, 0);
dist = ask(w) / A;
for (int i = 0; i < m; i++) {
int u, v;
u = U[i];
v = V[i];
mp[{v, u}] = mp[{u, v}] = i;
gr[u].push_back(v);
gr[v].push_back(u);
}
int l = -1;
int r = m - 1;
while (r - l > 1) {
int mid = (l + r) >> 1;
for (int i = 0; i <= mid; i++) {
w[i] = 1;
}
for (int i = mid + 1; i < m; i++) {
w[i] = 0;
}
ll T = ask(w);
if (T > dist * A) {
r = mid;
} else {
l = mid;
}
}
int a, b;
a = U[r];
b = V[r];
for (int i = 0; i < m; i++) {
w[i] = 0;
}
dfs(a, b);
int s, t;
ll asd = (ask(w) - dist * A) / (B - A);
l = -1;
r = vec[asd].size() - 1;
while (r - l > 1) {
int mid = (l + r) >> 1, v;
for (int i = 0; i < m; i++) {
w[i] = 0;
}
for (int i = 0; i <= mid; i++) {
v = vec[asd][i];
w[idc[v]] = 1;
}
ll T = ask(w);
if (T > A * dist) {
r = mid;
} else {
l = mid;
}
}
s = vec[asd][r];
for (int i = 0; i < maxn; i++) {
vec[i].clear();
}
h[s] = 0;
dfs(s, s);
asd = dist;
l = -1;
r = vec[asd].size() - 1;
while (r - l > 1) {
int mid = (l + r) >> 1, v;
for (int i = 0; i < m; i++) {
w[i] = 0;
}
for (int i = 0; i <= mid; i++) {
v = vec[asd][i];
w[idc[v]] = 1;
}
ll T = ask(w);
if (T > A * dist) {
r = mid;
} else {
l = mid;
}
}
t = vec[asd][r];
answer(s, t);
}
/*
7 6 4 5 0 3
0 2
1 2
2 3
3 4
4 5
4 6
2 1 1 2 0 1
0 1
*/
