#include "towns.h"
#include<bits/stdc++.h>
#define ll long long
#define pb push_back
#define ld long double
#define mp make_pair
#define F first
#define S second
#define pii pair<ll,ll>
using namespace :: std;
const ll maxn=700;
const ll inf=1e9+900;
ll fasta0[maxn];
ll sub,gn;
vector<pii> ger[maxn];
void addYal(ll a,ll b,ll w){
ger[a].pb(mp(b,w));
ger[b].pb(mp(a,w));
}
ll findFar(ll a,ll p=-1){
ll ans=0;
for(auto e:ger[a]){
if(e.F!=p){
ans=max(ans,findFar(e.F,a)+e.S);
}
}
return ans;
}
ll findSubTree(ll a,ll p=-1){
ll ans=(a<gn);
for(auto e:ger[a]){
if(e.F!=p){
ans+=findSubTree(e.F,a);
}
}
return ans;
}
bool isBAD(ll v){
for(auto e:ger[v]){
ll sz=findSubTree(e.F,v);
if(sz>gn/2){
return 1;
}
}
return 0;
}
pair<vector<ll> ,ll> shoa(ll n){
ll ans=inf;
vector<ll> vec;
for(ll i=0;i<n;i++){
ll r=findFar(i);
if(r<ans){
vec.clear();
ans=r;
}
if(r==ans){
vec.pb(i);
}
}
return mp(vec,ans);
}
int hubDistance(int n, int Sub) {
gn=n;
sub=Sub;
memset(fasta0,0,sizeof fasta0);
for(ll i=0;i<maxn;i++){
ger[i].clear();
}
pii far=mp(0,0);
for(ll i=1;i<n;i++){
fasta0[i]=getDistance(0,i);
far=max(far,mp(fasta0[i],i));
}
ll v=far.S;
ll u=0;
ll w=far.F;
vector<pair<ll,pii> > vec;
vector<ll> comp;
for(ll i=1;i<n;i++){
if(i!=v && i!=u){
ll a=getDistance(v,i);
ll b=getDistance(u,i);
ll s123=(a+b+w)/2;
ll s1=s123-a;
ll s2=s123-b;
ll s3=s123-w;
vec.pb(mp(i,mp(s1,s3)));
comp.pb(s1);
}
}
sort(comp.begin(),comp.end());
comp.resize(unique(comp.begin(),comp.end())-comp.begin());
addYal(u,n,comp[0]);
for(ll i=0;i+1<comp.size();i++){
addYal(n+i,n+i+1,comp[i+1]-comp[i]);
}
addYal(n+comp.size()-1,v,w-comp.back());
for(auto e:vec){
ll u=lower_bound(comp.begin(),comp.end(),e.S.F)-comp.begin();
addYal(e.F,n+u,e.S.S);
}
pair<vector<ll> ,ll> eee=shoa(n+comp.size());
ll r=eee.S;
if(sub<=2){
return r;
}
vector<ll> ves;
for(auto v:eee.F){
if(!isBAD(v)){
ves.pb(v);
}
}
if(ves.size()==0){
return -r;
}
if(ves.size()>1){
return r;
}
ll cent=ves[0];
vector<pii> ham;
for(auto e:ger[cent]){
if(e.F<n){
ham.pb(e);
}
}
if(ham.size()<=gn/2){
return r;
}
if(sub==4)return -r;
while(ham.size()){
pii ey=ham[rand()%ham.size()];
ll v=ey.F;
bitset<400> bi;
bi=0;
ll sum=0;
bi[v]=1;
for(auto e:ham){
ll u=e.F;
if(v!=u){
ll r=getDistance(v,u);
if(r!=e.S+ey.S){
bi[u]=1;
sum++;
}
}
}
if(sum>gn/2){
return -r;
}
vector<pii> newham;
for(auto e:ham){
if(!bi[e.F]){
newham.pb(e);
}
}
ham=newham;
}
return -r;
}
