#include "dreaming.h"
#include <vector>
#include <algorithm>
#define N 100001
#define INF 2000000000
using namespace std;
int n, L, out, max_len, MAX[4], gd[N];
bool check[N], gd_check[N];
vector<pair<int,int> > r[N];
int max_f(int x, int y) { return x>y?x:y; }
int min_f(int x, int y) { return x<y?x:y; }
int g(int lev, int up_node){
if(!gd_check[lev]){
gd_check[lev]=true;
for(vector<pair<int,int> >::iterator it=r[lev].begin(); it!=r[lev].end(); it++)
if(it->first!=up_node) gd[lev]=max_f(gd[lev],it->second+g(it->first,lev));
}
return gd[lev];
}
void f(int lev, int up_len){
int max1=0, max2=0, path, temp;
check[lev]=true;
for(vector<pair<int,int> >::iterator it=r[lev].begin(); it!=r[lev].end(); it++) {
if(!check[it->first]) temp=g(it->first,lev)+it->second;
else temp=up_len;
if(max1<temp){
max2=max1, max1=temp;
path=it->first;
}
else if(max2<temp) max2=temp;
}
out=max_f(out,max1+max2);
max_len=min_f(max_len,max1);
for(vector<pair<int,int> >::iterator it=r[lev].begin(); it!=r[lev].end(); it++)
if(!check[it->first]) f(it->first,(path==it->first?max2:max1)+it->second);
}
int travelTime(int _n, int m, int _L, int _a[], int _b[], int _t[]) {
int x, y, cnt=0;
n=_n, L=_L;
for(int i=0; i<m; i++){
x=_a[i]+1, y=_b[i]+1;
r[x].push_back({y,_t[i]}), r[y].push_back({x,_t[i]});
}
for(int i=1; i<=n; i++)
if(!check[i]){
max_len=INF, f(i,0);
cnt++;
MAX[0]=max_len, sort(MAX+0,MAX+4);
}
return max_f(out,max_f(cnt>1?MAX[3]+MAX[2]+L:0,cnt>2?MAX[2]+MAX[1]+L+L:0));
}
