#include <bits/stdc++.h>

using namespace std;

#define ll long long

struct arista
{
    int desde, hasta, costo;
};

vector <vector <arista> > ady;
vector <int> dist;
vector <bool> visit;

void DFS(int n)
{
    visit[n] = true;
    for(const auto &i:ady[n])
    {
        if(!visit[i.hasta])
        {
            dist[i.hasta] = dist[n]+i.costo;
            DFS(i.hasta);
        }
    }
}

int main()
{
    freopen("puesto.in", "r", stdin);
    freopen("puesto.out", "w", stdout);

    int n;
    cin >> n;

    ady.resize(300001);

    for(int i=0; i<n; i++)
    {
        int a, b, c;
        cin >> a >> b >> c;
        ady[a].push_back({a, b, c});
        ady[b].push_back({b, a, c});
    }

    dist = vector <int> (300001, 0);
    visit = vector <bool> (300001, false);
    DFS(1);
    int maxNodo = 1;
    for(int i=1; i<=300000; i++)
        if(dist[i] > dist[maxNodo])
            maxNodo = i;
    dist = vector <int> (300001, 0);
    visit = vector <bool> (300001, false);
    DFS(maxNodo);
    for(int i=1; i<=300000; i++)
        if(dist[i] > dist[maxNodo])
            maxNodo = i;

    printf("%.1f\n", dist[maxNodo]/2.0);

    return 0;
}