#include "dreaming.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int>vi;
#define pb push_back
#define sz(v) (int)v.size()
#define all(x) begin(x),end(x)
typedef pair<int,int>pi;
#define fi first
#define se second
typedef vector<pi>vpi;
#define eb emplace_back
#define FOR(i,a,b) for(int i=a; i<b; i++)
#define ROF(i,a,b) for(int i=b-1; i>=a; i--)
void ckmax(int &x, int y){x=max(x,y);}
void ckmin(int &x, int y){x=min(x,y);}
const int MX=1e5+10;
//-----------------------------
int N,M;
vpi adj[MX];
vi vis(MX,0);
vi dist(MX);
pi par[MX];
void dfs(int u){
vis[u]=1;
for(auto it: adj[u]){
int v=it.fi,w=it.se;
if(dist[v]==-1){
dist[v]=dist[u]+w;
par[v]={u,w};
dfs(v);
}
}
}
int U,V,diam;
void solve(int u){
FOR(i,0,N) dist[i]=-1; dist[u]=0;
dfs(u);
int v=u;
FOR(i,0,N) if(dist[i]!=-1 && dist[i]>dist[v]) v=i;
u=v;
FOR(i,0,N) dist[i]=-1; dist[u]=0;
dfs(u);
v=u;
FOR(i,0,N) if(dist[i]!=-1 && dist[i]>dist[v]) v=i;
diam=dist[v];
tie(U,V)={u,v};
}
int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
::N=N; ::M=M;
FOR(i,0,M){
int u=A[i],v=B[i],w=T[i];
adj[u].eb(v,w);
adj[v].eb(u,w);
}
int ans=0;
vi vec;
FOR(i,0,N) if(!vis[i]){
solve(i);
ckmax(ans,diam);
int cur=0,mn=diam;
while(U!=V){
cur+=par[V].se;
V=par[V].fi;
ckmin(mn,max(diam-cur,cur));
}
vec.pb(mn);
}
sort(all(vec));
reverse(all(vec));
//for(auto x: vec) cout << x << endl;
ckmax(ans,vec[0]+vec[1]+L);
if(sz(vec)>2){
ckmax(ans,vec[1]+vec[2]+L*2);
}
return ans;
}
/*
12
8
2
0 8 4
8 2 2
2 7 4
5 11 3
5 1 7
1 3 1
1 9 5
10 6 3
*/
/*
12
10
5
0 0 0 1 1 3 7 7 5 5
1 2 3 4 5 6 8 9 10 11
2 3 1 4 1 6 5 5 5 5
*/
