#include "highway.h"
#include <bits/stdc++.h>
int n, m;
std::vector <std::vector <int>> g;
long long dist;
void find_pair(int _n, std::vector <int> _u, std::vector <int> _v, int a, int b) {
n = _n;
m = _u.size();
g.resize(n);
for (int i = 0; i < m; i++) {
g[_u[i]].push_back(i);
g[_v[i]].push_back(i);
}
dist = ask(std::vector <int> (m, 0)) / a;
int onw = -1, onwe = -1;
{
std::vector <int> cur(m, 1);
int left = m;
while (left > 1) {
int mid = left / 2;
auto cop = cur;
for (int i = 0; i < m && left > mid; i++) {
if (cur[i]) {
cur[i] = 0;
left--;
}
}
long long val = ask(cur);
if (val >= (dist - 1) * a + b) {
left = 0;
for (int x : cur) {
left += x;
}
} else {
left = 0;
for (int i = 0; i < m; i++) {
if (cop[i] && !cur[i]) {
cop[i] = 1;
} else if (cop[i] && cur[i]) {
cop[i] = 0;
}
left += cop[i];
}
cur = cop;
}
}
assert(left == 1);
for (int i = 0; i < m; i++) {
if (cur[i]) {
onw = _u[onwe = i];
break;
}
}
assert(onw != -1);
}
int dtf = -1;
std::vector <int> par(n, -1);
std::vector <std::vector <int>> ofd(n + 1);
{
int half = dist / 2;
std::vector <int> cur(m, 1);
std::queue <std::pair <int, std::pair <int, int>>> q;
std::vector <bool> vis(n, false);
q.push({ -1, { onw, 0 } });
while (q.size()) {
int v = q.front().second.first;
int w = q.front().second.second;
int pa = q.front().first;
q.pop();
if (vis[v]) {
continue;
}
vis[v] = true;
par[v] = pa;
ofd[w].push_back(v);
if (w <= half) {
cur[pa] = 0;
}
for (int x : g[v]) {
int to = _u[x] ^ _v[x] ^ v;
q.push({ x, { to, w + 1 } });
}
}
long long val = ask(cur);
val -= dist * a;
int heavies = val / (b - a);
dtf = half + heavies;
}
if (dtf == dist / 2) {
dtf++;
onw = _v[onwe];
par = std::vector <int> (n, -1);
ofd = std::vector <std::vector <int>> (n + 1);
std::queue <std::pair <int, std::pair <int, int>>> q;
std::vector <bool> vis(n, false);
q.push({ -1, { onw, 0 } });
while (q.size()) {
int v = q.front().second.first;
int w = q.front().second.second;
int pa = q.front().first;
q.pop();
if (vis[v]) {
continue;
}
vis[v] = true;
par[v] = pa;
ofd[w].push_back(v);
for (int x : g[v]) {
int to = _u[x] ^ _v[x] ^ v;
q.push({ x, { to, w + 1 } });
}
}
}
int s = -1;
{
std::vector <int> cur(m, 0);
int left = ofd[dtf].size();
while (left > 1) {
int mid = left / 2;
auto cop = cur;
for (int i = 0; i < (int) ofd[dtf].size() && left > mid; i++) {
if (!cur[ofd[dtf][i]]) {
cur[ofd[dtf][i]] = 1;
left--;
}
}
long long val = ask(cur);
if (val == dist * a) {
left = 0;
for (int x : ofd[dtf]) {
left += !cur[x];
}
} else {
left = 0;
for (int i = 0; i < (int) ofd[dtf].size(); i++) {
if (!cur[ofd[dtf][i]]) {
cop[ofd[dtf][i]] = 1;
}
left += !cop[ofd[dtf][i]];
}
cur = cop;
}
}
assert(left == 1);
for (int x : ofd[dtf]) {
if (!cur[par[x]]) {
s = x;
break;
}
}
assert(s != -1);
}
std::vector <int> cand;
{
std::vector <int> ok(n, 0);
for (int x : ofd[dist - dtf]) {
ok[x]++;
}
std::queue <std::pair <int, int>> q;
q.push({ s, 0 });
std::vector <bool> vis(n, false);
while (q.size()) {
int v = q.front().first;
int w = q.front().second;
q.pop();
if (vis[v]) {
continue;
}
vis[v] = true;
ok[v] += w == dist;
for (int x : g[v]) {
int to = _u[x] ^ _v[x] ^ v;
q.push({ to, w + 1 });
}
}
for (int i = 0; i < n; i++) {
if (ok[i] == 2) {
cand.push_back(i);
}
}
assert(cand.size());
}
int e = -1;
{
std::vector <int> cur(m, 0);
int left = cand.size();
while (left > 1) {
int mid = left / 2;
auto cop = cur;
for (int i = 0; i < (int) cand.size() && left > mid; i++) {
if (!cur[par[cand[i]]]) {
cur[par[cand[i]]] = 1;
left--;
}
}
long long val = ask(cur);
if (val == dist * a) {
left = 0;
for (int x : cand) {
left += !cur[x];
}
} else {
left = 0;
for (int i = 0; i < (int) cand.size(); i++) {
if (!cur[par[cand[i]]]) {
cop[par[cand[i]]] = 1;
}
left += !cop[par[cand[i]]];
}
cur = cop;
}
}
assert(left == 1);
for (int x : cand) {
if (!cur[par[x]]) {
e = x;
break;
}
}
assert(e != -1);
}
answer(s, e);
}
