#include "highway.h"
#include "bits/stdc++.h"
#define MAXN 130009
#define INF 1000000007
#define mp(x,y) make_pair(x,y)
#define all(v) v.begin(),v.end()
#define pb(x) push_back(x)
#define wr cout<<"----------------"<<endl;
#define ppb() pop_back()
#define tr(ii,c) for(__typeof((c).begin()) ii=(c).begin();ii!=(c).end();ii++)
#define ff first
#define ss second
#define my_little_dodge 46
#define debug(x) cerr<< #x <<" = "<< x<<endl;
using namespace std;
typedef long long ll;
typedef pair<int,int> PII;
template<class T>bool umin(T& a,T b){if(a>b){a=b;return 1;}return 0;}
template<class T>bool umax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
int M,N;
PII edge[MAXN];
vector<int>A,B,AA,BB;
vector<PII>adj[MAXN],gr[MAXN];
bool check(){
if(A.empty() or B.empty())
return 0;
vector<int>col(N),w(M);
tr(it,A)col[*it]=0;
tr(it,B)col[*it]=1;
for(int i=0;i<M;i++)
w[i]=(col[edge[i].ff]==col[edge[i].ss]);
return ask(w)%2;
}
void find_pair(int N, vector<int> U, vector<int> V, int a, int b) {
M=U.size();::N=N;
for(int i=0;i<M;i++)
edge[i]=mp(U[i],V[i]);
if(a==1 and b==2){//Subtask 5
int hor=0,who=-1;
for(int i=0;i<17;i++){
A.clear();B.clear();
for(int j=0;j<N;j++){
if(j>>i&1)A.pb(j);
else B.pb(j);
}
if(check()) hor^=(1<<i),who=i;
}A.clear();B.clear();assert(who!=-1);
for(int j=0;j<N;j++){
if(j>>who&1)A.pb(j);
else B.pb(j);
}int sz=A.size();
while(sz>1){
AA=A;BB=B;
A.clear();
for(int i=0;i<sz/2;i++)A.pb(AA[i]);
for(int i=sz/2;i<sz;i++)B.pb(AA[i]);
if(!check()){
B=BB;A.clear();
for(int i=sz/2;i<sz;i++)
A.pb(AA[i]);
}sz=A.size();
}
answer(A[0],A[0]^hor);
return;
}
vector<int>w(M,0),ans;
ll dis=ask(w);
int low=0,high=M-1;
while(low<high){
int mid=(low+high)>>1;
for(int i=0;i<M;i++)
w[i]=(i>mid);
if(ask(w)==dis)
high=mid;
else
low=mid+1;
}int v=edge[low].ff;
for(int i=0;i<M;i++)w[i]=1;
vector<int>vis(N),d(N);
for(int i=0;i<N;i++)
vis[i]=0,d[i]=INF;
for(int i=0;i<M;i++){
gr[edge[i].ff].pb(mp(edge[i].ss,i));
gr[edge[i].ss].pb(mp(edge[i].ff,i));
}
priority_queue<PII>p;
p.push(mp(0,v));d[v]=0;
while(!p.empty()){
int nd=p.top().ss;
p.pop();
if(vis[nd])
continue;
vis[nd]=1;
tr(it,gr[nd]){
if(d[it->ff]>d[nd]+1){
d[it->ff]=d[nd]+1;w[it->ss]=0;
p.push(mp(-d[it->ff],it->ff));
}
}
}
vector<int>id(N),par(M);
int s=v;
// printf("BFSTREE:\n");
//debug(v);
for(int i=0;i<M;i++)
if(!w[i]){
//printf("%d %d\n",edge[i].ff,edge[i].ss);
adj[edge[i].ff].pb(mp(edge[i].ss,i));
adj[edge[i].ss].pb(mp(edge[i].ff,i));
}
for(int j=0;j<2;j++){int tmp=0;
for(int i=0;i<N;i++)vis[i]=0;
queue<int>q;q.push(s);vis[s]=1;
while(!q.empty()){
int nd=q.front();q.pop();
tr(it,adj[nd])
if(!vis[it->ff]){
id[tmp++]=it->ss;par[it->ss]=it->ff;
vis[it->ff]=1;q.push(it->ff);
}
}
int st=0,en=N-2;
while(st<en){
int mid=(st+en+1)>>1;
for(int i=0;i<N-1;i++)
w[id[i]]=(i>=mid);
if(ask(w)==dis)en=mid-1;
else st=mid;
}s=par[id[st]];
ans.pb(s);
}
answer(ans[0],ans[1]);
}
