#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 s = 0;
//int onw = -1, onwe = -1;
//{
//std::vector <int> cur(m, 0);
//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] = 1;
//left--;
//}
//}
//long long val = ask(cur);
//val -= dist * a;
//int hea_now = val / (b - a);
//if (hea_now < dist) {
//left = 0;
//for (int x : cur) {
//left += !x;
//}
//} else {
//left = 0;
//for (int i = 0; i < m; i++) {
//if (!cur[i]) {
//cop[i] = 1;
//}
//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> par(n, -1);
{
std::queue <std::pair <int, int>> q;
q.push({ s, -1 });
std::vector <bool> vis(n, false);
while (q.size()) {
int v = q.front().first;
int p = q.front().second;
q.pop();
if (vis[v]) {
continue;
}
vis[v] = true;
par[v] = p;
for (int x : g[v]) {
int to = _u[x] ^ _v[x] ^ v;
q.push({ to, x });
}
}
}
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) {
if (ok[i] == 1) {
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);
}
