#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;
}
signed char rad(ll n, ll p, ll d, ll e, unordered_set<ll> &dist) {
if (n == e) return 1;
signed char found = 0;
for(pair<ll,ll> c: adj[n]) {
if (c.F == p) continue;
if (rad(c.F, n, d + c.S, e, dist) == 1) found = 1;
}
if (found) dist.insert(d);
return found;
}
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;
// 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
FOR(i, N) {
if (vis[i]) continue;
ll startp = mxDist(i, -1, 0).S;
auto [diam, endp] = mxDist(startp, -1, 0);
res = max(res, diam);
unordered_set<ll> dist;
rad(startp, -1, 0, endp, dist);
ll minrad = 1e18;
for(ll d: dist) minrad = min(minrad, max(d, diam - d));
if (minrad == 1e18) radii.push_back(0);
else radii.push_back(minrad);
}
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;
}
