#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define FOR(i,N) for(ll i = 0; i < N; i++)
#define all(x) (x).begin(), (x).end()
#define F first
#define S second
#include "dreaming.h"
ll N, M, L;
vector<vector<pair<ll,ll>>> adj;
vector<signed char> vis;
pair<ll,ll> mxDist(ll n, ll p, ll d) {
vis[n] = 1;
pair<ll,ll> ans = {d, n}; // furthest dist, furthest node
for(pair<ll,ll> c: adj[n]) {
if (c.F == p) continue;
pair<ll,ll> ret = mxDist(c.F, n, d + c.S);
if (ret.F > ans.F) ans = ret;
}
return ans;
}
pair<ll,ll> calc(ll n, ll p, ll d){
// let optimal node = node in a tree that best splits the diameter in half
// let radii = maximum distance from any node in a tree to optimal node
pair<ll,ll> ans = {d, 1e18}; // diameter, radii
for(pair<ll,ll> c: adj[n]) {
if (c.F == p) continue;
pair<ll,ll> ret = calc(c.F, n, d + c.S);
if (ret.F > ans.F) ans = ret;
if (ret.F == ans.F) ans.S = min(ans.S, ret.S);
}
// if we're still in the second (deeper) half of the tree diameter's path
if (d*2 >= ans.F) ans.S = d;
return ans;
}
int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
::N = N, ::M = M, ::L = L;
adj.resize(N);
vis.resize(N);
FOR(i, M) {
adj[A[i]].push_back({B[i], T[i]});
adj[B[i]].push_back({A[i], T[i]});
}
ll res = 0;
vector<ll> radii;
FOR(i, N) {
if (vis[i]) continue;
auto [diam, rad] = calc(mxDist(i, -1, 0).S, -1, 0);
res = max(res, diam);
radii.push_back(rad);
}
sort(all(radii));
reverse(all(radii));
// connect tree with the largest radii to all other trees (via respective optimal nodes)
if ((ll)radii.size() >= 2) res = max(radii[0] + radii[1] + L, res);
if ((ll)radii.size() >= 3) res = max(radii[1] + radii[2] + L*2, res);
return (int)res;
}
