#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll N4=9e4;
#define MID ((l+r)/2)
vector<ll> t[N4];
ll d[N4];
void dfs(ll curr, ll prev){
for(auto nxt:t[curr]){
if(nxt==prev) continue;
d[nxt]=d[curr]+1;
dfs(nxt,curr);
}
}
ll y[N4]={};
bool mark(ll curr, ll prev, ll x){
if(curr==x) y[curr]=1;
for(auto nxt:t[curr]){
if(nxt==prev) continue;
if(mark(nxt,curr,x)) y[curr]=1;
}
return y[curr];
}
void find_pair(int n, vector<int> u, vector<int> v, int a, int b){
for(ll i=0; i<n-1; i++){
t[u[i]].push_back(v[i]);
t[v[i]].push_back(u[i]);
}
d[0]=0;
dfs(0,0);
ll maxd=0;
for(ll i=0; i<n; i++){
maxd=max(maxd,d[i]);
}
ll dist=ask(vector<int>(n-1,0));
ll calls=1;
ll l=0, r=maxd-1, d1=maxd;
while(l<=r){
vector<int> x1(n-1,0), x2(n-1,0);
for(ll i=0; i<n-1; i++){
if(max(d[u[i]],d[v[i]])<=MID) x1[i]=1;
if(max(d[u[i]],d[v[i]])<=MID+1) x2[i]=1;
}
ll dist1=ask(x1), dist2=ask(x2);
calls+=2;
assert(calls<=100);
if(dist2-dist1==b-a || dist1*a==dist*b){
d1=MID;
r=MID-1;
}
else l=MID+1;
}
l=0; r=maxd;
ll d2=d1;
while(l<=r){
vector<int> x(n-1,0);
for(ll i=0; i<n-1; i++){
if(min(d[u[i]],d[v[i]])>=MID) x[i]=1;
}
calls++;
assert(calls<=100);
if(ask(x)==dist){
d2=MID;
r=MID-1;
}
else l=MID+1;
}
// cout<<d1<<" "<<d2<<endl;
vector<ll> e1, e2;
for(ll i=0; i<n-1; i++){
if(max(d[u[i]],d[v[i]])==d1) e1.push_back(i);
if(max(d[u[i]],d[v[i]])==d2) e2.push_back(i);
}
l=0; r=e2.size()-1;
ll idx2;
while(l<=r){
vector<int> x(n-1,0);
for(ll i=l; i<=MID; i++){
x[e2[i]]=1;
}
calls++;
assert(calls<=100);
if(ask(x)>dist){
idx2=MID;
r=MID-1;
}
else l=MID+1;
}
ll ans2;
if(d[u[e2[idx2]]]==d2) ans2=u[e2[idx2]];
else ans2=v[e2[idx2]];
mark(0,0,ans2);
ll z=-2;
for(ll i=0; i<n; i++){
// cout<<i<<" "<<y[i]<<" "<<d[i]<<endl;
if(y[i] && d[i]==d1) z=i;
}
l=0; r=e1.size()-1;
ll idx1=-1;
while(l<=r){
vector<int> x(n-1,0);
for(ll i=l; i<=MID; i++){
if(u[e1[i]]!=z && v[e1[i]]!=z) x[e1[i]]=1;
}
calls++;
assert(calls<=100);
if(ask(x)>dist){
idx1=MID;
r=MID-1;
}
else l=MID+1;
}
ll ans1;
if(idx1==-1) ans1=z;
else if(d[u[e1[idx1]]]==d1) ans1=u[e1[idx1]];
else ans1=v[e1[idx1]];
answer(ans1,ans2);
// cout<<ans1<<" "<<ans2<<endl;
}
