#include <bits/stdc++.h>
#include "dreaming.h"
#define MAXN 100009
#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;}
vector<PII>adj[MAXN];
int mx,mn=INF,who,d[MAXN][2],vis[MAXN];
void dfs(int nd,int pr,int lvl){
if(umax(mx,lvl))who=nd;
tr(it,adj[nd])
if(it->ff!=pr)
dfs(it->ff,nd,lvl+it->ss);
}vector<int>v;
void dfs1(int nd,int pr,int t,int lvl=0){
d[nd][t]=lvl;v.pb(nd);
tr(it,adj[nd])
if(it->ff!=pr)
dfs1(it->ff,nd,t,lvl+it->ss);
}
void dfs2(int nd,int pr){
umin(mn,max(d[nd][0],d[nd][1]));
vis[nd]=1;
tr(it,adj[nd])
if(it->ff!=pr)
dfs2(it->ff,nd);
}
int travelTime(int n,int m,int l,int a[],int b[],int t[]){
if(n==1)return 0;int dia=0;
for(int i=0;i<m;i++)
adj[a[i]].pb(mp(b[i],t[i])),adj[b[i]].pb(mp(a[i],t[i]));
vector<int>v;
for(int i=0;i<n;i++)
if(!vis[i]){
mx=-1,dfs(i,-1,0);int a=who;
mx=-1,dfs(a,-1,0);int b=who;
dfs1(a,-1,0);dfs1(b,-1,1);
umax(dia,mx);dfs2(i,-1);
v.pb(mn);mn=INF;
}
sort(all(v));reverse(all(v));
if(int(v.size())==1)
return dia;
if(int(v.size())==2)
return max(dia,v[0]+v[1]+l);
return max(dia,max(v[0]+v[1]+l,v[1]+v[2]+l+l));
}
