#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,0);
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);vi lf(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;
lf[k]=0;
dist[u.F]=dist[k]+1;
p[u.F]=k;
val[u.F]=u.S;
pq.push(u.F);
}
}
REP(i,0,n)if(p[i]==0)p[i]=i;
vii parent(n,vi(log2(n)+3));
REP(i,0,n)parent[i][0]=p[i];
REP(j,1,log2(n)+2)REP(i,0,n)parent[i][j]=parent[parent[i][j-1]][j-1];
vi bb;
REP(i,1,n)if(lf[i]==1)bb.PB(i);
int s=bb.size();
int minv=dist[bb[0]],maxv=dist[bb[0]];
REP(i,0,s){
minv=min(minv,dist[bb[i]]);
maxv=max(maxv,dist[bb[i]]);
}
int l=minv-maxv,r=n-1;
while(l!=r){
arr.clear();
arr.resize(m,0);
int mid=floor((l+r)/(double)2);
REP(i,0,s){
int e=mid+dist[bb[i]]-minv;
if(e<0)continue;
int q=bb[i];
while(e>=0){
if(arr[val[q]]==1)break;
arr[val[q]]=1;
q=p[q];
e--;
}
}
if(ask(arr)>d*A)r=mid;
else l=mid+1;
}
vi b;
REP(i,0,s){
int e=l+dist[bb[i]]-minv;
if(e<0)continue;
int q=bb[i];
while(e>0){
int f=LSOne(e);
q=parent[q][log2(f)];
e-=f;
}
b.PB(q);
}
s=b.size();
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;
}
int ans1=b[l];
dist.clear();
dist.resize(n,-1);
pq.push(ans1);dist[ans1]=0;
p.clear();
p.resize(n,-1);
val.clear();val.resize(n,-1);
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);
}
}
b.clear();
REP(i,0,n)if(dist[i]==d)b.PB(i);
s=b.size();
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(ans1, b[l]);
}
