#include "highway.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vii;
typedef pair<int,int> pi;
typedef vector<pi> pii;
typedef tuple<int,int,int> tii;
typedef vector<ll> li;
typedef vector<li> lii;
#define REP(i,a,b) for(int i=a;i<b;i++)
#define F first
#define S second
#define PB push_back
#define MP make_pair
#define LSOne(s) ((s)&(-s))
ll INF=1e18+10;
int inf=1e9+10;
ll MD=1e9+7;
void find_pair(int n, std::vector<int> U, std::vector<int> V, int A, int B) {
int m = U.size();
vi arr(m);
REP(i,0,m)arr[i]=0;
long long d=ask(arr)/A;
vi p(n,-1);
vi val(n,-1);
vector<vector<pi>> a(n);
REP(i,0,m){
a[U[i]].PB({V[i],i});
a[V[i]].PB({U[i],i});
}
queue<int> pq;
vi dist(n,-1);
pq.push(0);dist[0]=0;
while(!pq.empty()){
int k=pq.front();
pq.pop();
for(auto u:a[k]){
if(p[k]==u.F)continue;
dist[u.F]=dist[k]+1;
p[u.F]=k;
val[u.F]=u.S;
pq.push(u.F);
}
}
vi b;
REP(i,0,n)if(dist[i]==d)b.PB(i);
int s=b.size();
int l=0,r=s-1;
while(l!=r){
arr.clear();
arr.resize(m,0);
int mid=(l+r)/2;
REP(i,0,mid+1)arr[val[b[i]]]=1;
if(ask(arr)>d*A)r=mid;
else l=mid+1;
}
answer(0, b[l]);
}
