#include "highway.h"
#include<bits/stdc++.h>
using namespace std;
constexpr int N = 1e5 + 5;
vector<int> w, lst;
vector<pair<int, int> > edges[N];
int n, m, a, b, d[N], s, t;
long long alap;
void dfs(int id, int de = 0, int par = -1){
d[id] = de;
for(pair<int, int> p : edges[id]){
if(p.first != par){
dfs(p.first, de + 1, id);
lst.push_back(p.second);
}
}
}
int src(int l, int r){
if(l == r) return (l == lst.size() ? -1 : lst[l]);
int m = (l + r) / 2;
for(int i = max(0, l); i <= m; i++) w[lst[i]] = 1;
long long cur = ask(w);
for(int i = max(0, l); i <= m; i++) w[lst[i]] = 0;
return (cur > alap ? src(l, m) : src(m + 1, r));
}
void find_pair(int _N, std::vector<int> u, std::vector<int> v, int A, int B) {
n = _N;
m = u.size();
a = A;
b = B;
w.assign(m, 0);
alap = ask(w);
for(int i = 0; i < m; i++){
edges[u[i]].emplace_back(v[i], i);
edges[v[i]].emplace_back(u[i], i);
}
dfs(0);
sort(lst.begin(), lst.end(), [&u, &v](int x, int y){return max(d[u[x]], d[v[x]]) > max(d[u[y]], d[v[y]]);});
int id = src(0, lst.size() - 1);
pair<int, int> p1 = make_pair(u[id], v[id]), p2;
lst.clear();
dfs(p1.first, 0, p1.second);
if(lst.empty()){
s = p1.first;
}
else{
sort(lst.begin(), lst.end(), [&u, &v](int x, int y){return max(d[u[x]], d[v[x]]) > max(d[u[y]], d[v[y]]);});
id = src(0, lst.size());
if(id == -1) s = p1.first;
else s = (d[u[id]] > d[v[id]] ? u[id] : v[id]);
}
swap(p1.first, p1.second);//ugyanez forditva
lst.clear();
dfs(p1.first, 0, p1.second);
if(lst.empty()){
t = p1.first;
}
else{
sort(lst.begin(), lst.end(), [&u, &v](int x, int y){return max(d[u[x]], d[v[x]]) > max(d[u[y]], d[v[y]]);});
id = src(0, lst.size());
if(id == -1) t = p1.first;
else t = (d[u[id]] > d[v[id]] ? u[id] : v[id]);
}
lst.clear();
answer(s, t);
}
