#include <bits/stdc++.h>

using namespace std;

#define forsn(i, s, n) for(int i=s;i<int(n);i++)
#define forn(i, n) forsn(i, 0, n)
#define all(v) v.begin(), v.end()
#define NACHO ios_base::sync_with_stdio(0);cin.tie(NULL);

vector<bool> visited;

void dfs(int node, vector<vector<pair<int,int>>> &adj, vector<int> &dist){
    visited[node] = 1;
    for(auto u : adj[node]){
        if(!visited[u.first]){
            dist[u.first] = dist[node]+u.second;
            dfs(u.first, adj, dist);
        }
    }
}

int main(){
    //ifstream cin("puesto.in");
    //ofstream cout("puesto.out");
    int m; cin >> m;
    vector<vector<pair<int,int>>> adj (300001);
    forn(i, m){
        int u, v, w; cin >> u >> v >> w;
        u--; v--;
        adj[u].push_back({v, w});
        adj[v].push_back({u, w});
    }
    visited.resize(300001, 0);
    vector<int> dist (300001, 0);
    dfs(0, adj, dist);
    int nodito;
    int maxi = 0;
    forn(i, 300001){
        if(dist[i] > maxi){
            maxi = dist[i];
            nodito = i;
        }
    }
    visited.resize(300001, 0);
    dist.resize(300001, 0);
    dfs(nodito, adj, dist);
    maxi = 0;
    forn(i, 300001){
        maxi = max(maxi, dist[i]);
    }
    printf("%.1f\n", maxi/2.0);
}