#include <bits/stdc++.h>
#include "highway.h"
using namespace std;
using ll = long long;
using pii = pair<int, int>;
vector<vector<pii>> adj;
vector<int> endp;
vector<int> edge;
int t;
vector<int> query;
ll w;
int first(int M) {
int l = 0, r = M-1;
int ans = 0;
while (l <= r) {
int m = (l+r)/2;
for (int i=0; i<M; i++) {
query[i] = (i <= m);
}
ll w2 = ask(query);
if (w2 != w) {
r=m-1;
}
else {
l = m+1;
ans = m+1;
}
}
return ans;
}
int last(int M) {
int l=0, r = t-1;
int ans=-1;
while (l <= r) {
int m = (l+r+1)/2;
for (int i=0; i<M; i++) {
query[i] = (edge[i] >= m);
}
ll w2 = ask(query);
if (w2 != w) {
l = m+1;
ans = m;
}
else {
r = m-1;
}
}
return ans;
}
void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
int m = U.size();
query.assign(m, 0);
w = ask(query);
adj.resize(N);
for (int i=0; i<m; i++) {
int a = U[i];
int b = V[i];
adj[a].push_back({i, b});
adj[b].push_back({i, a});
}
edge.resize(m);
endp.resize(m);
vector<int> ans(2);
int e = first(m);
vector<int> disv[2];
vector<int> v = {U[e], V[e]};
for (int i=0; i<2; i++) {
queue<int> q;
vector<int> dis(N, -1);
dis[v[i]] = 0;
q.push(v[i]);
while (!q.empty()) {
int u = q.front();
q.pop();
for (auto x : adj[u]) {
if (dis[x.second] == -1) {
dis[x.second] = dis[u]+1;
q.push(x.second);
}
}
}
disv[i] = dis;
}
for (int i=0; i<2; i++) {
edge.assign(m, -1);
t = 0;
queue<int> q;
vector<int> dis(N, -1);
dis[v[i]] = 0;
q.push(v[i]);
while (!q.empty()) {
int u = q.front();
q.pop();
for (auto x : adj[u]) {
if (disv[i][x.second] < disv[1-i][x.second]) {
if (dis[x.second] == -1) {
dis[x.second] = dis[u]+1;
endp[t] = x.second;
edge[x.first] = t++;
q.push(x.second);
}
else if (dis[x.second] == dis[u]+1) {
edge[x.first] = N;
}
}
else if (x.first != e) {
edge[x.first] = N;
}
}
}
int le = last(m);
ans[i] = (le == -1 ? v[i] : endp[le]);
}
answer(ans[0], ans[1]);
}
