#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pb push_back
#define all(x) x.begin(), x.end()
#define allr(x) x.rbegin(), x.rend()
#define mp make_pair
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef complex<double> cd;
const int MAXN = 9e4+10;
int depth[MAXN], id[MAXN];
vector<pii> adj[MAXN];
void dfs(int ver, int prev){
depth[ver]=depth[prev]+1;
for(auto [u, v] : adj[ver]){
if(u==prev) continue;
id[u]=v;
dfs(u, ver);
}
}
void find_pair(int N, vector<int> U, vector<int> V, int A, int B) {
int M=(int)U.size();
for(int i=0;i<M;i++){
adj[U[i]].pb({V[i], i});
adj[V[i]].pb({U[i], i});
}
vector<int> w(M, 0);
ll comp=ask(w);
dfs(0, 0);
vector<int> proc(N);
iota(all(proc), 0);
sort(all(proc), [&](int a, int b){ return depth[a]>depth[b]; });
int low=0, high=N-2, best=-1;
while(low<=high){
int mid=(low+high)>>1;
for(int i=0;i<=mid;i++) w[id[proc[i]]]=1;
ll curr=ask(w);
for(int i=0;i<=mid;i++) w[id[proc[i]]]=0;
if(curr>comp){
best=mid;
high=mid-1;
}
else low=mid+1;
}
int s=proc[best];
depth[s]=0;
dfs(s, s);
sort(all(proc), [&](int a, int b){ return depth[a]>depth[b]; });
low=0; high=N-2; best=-1;
while(low<=high){
int mid=(low+high)>>1;
for(int i=0;i<=mid;i++) w[id[proc[i]]]=1;
ll curr=ask(w);
for(int i=0;i<=mid;i++) w[id[proc[i]]]=0;
if(curr>comp){
best=mid;
high=mid-1;
}
else low=mid+1;
}
int t=proc[best];
answer(s, t);
}
