#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> PP;
// #define MOD 1000000007
#define MOD 998244353
#define INF 2305843009213693951
#define PI 3.141592653589
#define setdouble setprecision
#define REP(i,n) for(ll i=0;i<(n);++i)
#define OREP(i,n) for(ll i=1;i<=(n);++i)
#define RREP(i,n) for(ll i=(n)-1;i>=0;--i)
#define ORREP(i,n) for(ll i=(n);i>=1;--i)
#define rep(i,a,b) for(ll i=(a);i<=(b);++i)
#define ALL(v) (v).begin(), (v).end()
#define chmin(k,m) k = min(k,m)
#define chmax(k,m) k = max(k,m)
#define GOODBYE do { cout << "-1" << endl; return 0; } while (false)
#define MM <<" "<<
#define Endl endl



int main(void){
    //cin.tie(nullptr);
    //ios::sync_with_stdio(false);

    ll N;
    cin >> N;
    vector<vector<pair<ll,ll>>> G(N);
    REP(i,N-1){
        ll u,v,w;
        cin >> u >> v >> w;
        u--;v--;
        G[u].push_back({v,w});
        G[v].push_back({u,w});
    }

    function<void(ll,ll,vector<ll>&)> dfs = [&](ll v, ll p,vector<ll>& d){

        for(pair<ll,ll> q:G[v]){
            ll e = q.first, w = q.second;
            if(e==p)continue;
            d[e] = d[v]+w;
            dfs(e,v,d);
        }

    };
    
    vector<ll> dist1(N,INF);
    dist1[0]=0;
    dfs(0,-1,dist1);

    ll u = 0;
    REP(i,N){if(dist1[i]>dist1[u])u=i;}
    
    vector<ll> dist2(N,INF);
    dist2[u]=0;
    dfs(u,-1,dist2);

    ll Ans = 0;
    REP(i,N){
        Ans = max(Ans,dist2[i]);
    }
    cout << Ans << endl;
    
    return 0;
    
}