#include "dreaming.h"
#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>
#define ll long long
using namespace std;
const int mxN = 1e6;
const ll INF = 1e15;
ll n, m, l;
int travelTime(int N, int M, int L, int A[], int B[], int T[]);
vector<pair<ll, ll>> pov[mxN];
ll td[mxN];
bool vis[mxN];
ll maxd = 0, cnt = 0;
pair<ll, ll> dfs(ll u, ll par) {
pair<ll, ll> ans = { 0,u };
vis[u] = true;
for (auto p : pov[u]) {
ll v = p.first;
ll c = p.second;
if (v != par) {
pair<ll, ll> q = dfs(v, u);
q.first += c;
ans = max(ans, q);
}
}
return ans;
}
ll opt = INF;
ll opt_dfs(ll u, ll tar, ll d, ll par)
{
if (u == tar) {
opt = d;
return d;
}
ll ans = INF;
for (auto p : pov[u]) {
ll v = p.first;
ll c = p.second;
if (v != par) {
ll dis = opt_dfs(v, tar, d, u) - c;
ans = min(ans, dis);
}
}
opt = min(max(ans,d-ans), opt);
return ans;
}
int travelTime(int N, int M, int L, int A[], int B[], int T[]) {
ll n = N; ll m = M; ll l = L;
for (ll i = 0; i < m; i++) {
ll a = A[i], b = B[i], c = T[i];
pov[a].push_back({ b,c });
pov[b].push_back({ a,c });
}
memset(vis, 0, n);
for (ll i = 0; i < n; i++) {
if (!vis[i] && pov[i].size() <= 1) {
pair<ll, ll> p = dfs(i, -1);
pair<ll, ll> q = dfs(p.second, -1);
maxd = max(maxd,q.first);
opt = INF;
opt_dfs(p.second, q.second, q.first, -1);
td[cnt] = -opt;
cnt++;
}
}
if (cnt == 1) { return maxd; }
sort(td, td + cnt);
ll ans = l - td[0] - td[1];
if (cnt > 2) { ans = max(ans, 2 * l - td[1] - td[2]); }
return max(maxd,ans);
}
