#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
#define OPTM ios_base::sync_with_stdio(0); cin.tie(0);
#define INF int(1e9+7)
#define ln '\n'
#define ll long long
#define ull unsigned long long
#define ui unsigned int
#define us unsigned short
#define FOR(i,s,n) for (int i = s; i < n; i++)
#define FORR(i,n,s) for (int i = n; i > s; i--)
#define FORX(u, arr) for (auto u : arr)
#define PB push_back
#define in(v,x) (v.find(x) != v.end())
#define F first
#define S second
#define PII pair<int, int>
#define PLL pair<ll, ll>
#define UM unordered_map
#define US unordered_set
#define PQ priority_queue
#define ALL(v) v.begin(), v.end()
const ll LLINF = 1e18+1;
#define int long long
struct Edge {
int x,y,depth;
};
const int MAXN = 9e4+5;
int n,m;
vector<PII> v[MAXN];
vector<int32_t> w, tour;
vector<Edge> e;
int d[MAXN], ans;
void dfs(int s, int pa) {
FORX(u,v[s]) {
if (u.F == pa) continue;
if (e[u.S].y != u.F) swap(e[u.S].x, e[u.S].y);
tour.PB(u.S);
dfs(u.F,s);
}
}
int find_end(int s, int pa) {
tour.clear();
dfs(s,pa);
// FORX(u,tour) cout << u << " ";
// cout << ln;
int l = -1, r = tour.size()-1;
while (l < r) {
FOR(i,0,m) w[i] = 0;
int mid = (l+r+1)/2;
FOR(i,mid,r+1) w[tour[i]] = 1;
int val = ask(w);
if (val == ans) r = mid-1;
else l = mid;
}
// cout << "s l: " << s << " " << l << ln;
return (l == -1 ? s : e[tour[l]].y);
}
void find_pair(int32_t N, std::vector<int32_t> U, std::vector<int32_t> V, int32_t A, int32_t B) {
n = N; m = U.size();
FOR(i,0,m) {
v[U[i]].PB({V[i],i});
v[V[i]].PB({U[i],i});
e.PB({U[i],V[i],-1LL});
}
dfs(0,-1);
FOR(i,0,m) w.PB(0);
ans = ask(w);
// find intermediate edge
int l = 0, r = m-1;
while (l < r) {
FOR(i,0,n) w[i] = 0;
int mid = (l+r+1)/2;
FOR(i,mid,r+1) w[tour[i]] = 1;
int val = ask(w);
// cout << "m a: " << mid << " " << val << ln;
if (val == ans) r = mid-1;
else l = mid;
}
int xs = e[tour[l]].x, ys = e[tour[l]].y;
// cout << "xs ys: " << xs << " " << ys << ln;
int32_t S = ys, T = find_end(xs,ys);
// cout << "S T: " << S << " " << T << ln;
answer(S,T);
}
