#include <bits/stdc++.h>
using namespace std;

#define ALL(x) (x).begin(),(x).end()
#define IO ios::sync_with_stdio(false),cin.tie(nullptr);
#define LB(v, x) (ll)(lower_bound(ALL(v),x)-(v).begin())
#define UQ(v) sort(ALL(v)),(v).erase(unique(ALL(v)),v.end())
#define REP(i, n) for(ll i=0; i<(ll)(n); i++)
#define FOR(i, a, b) for(ll i=(ll)(a); (a)<(b) ? i<(b) : i>(b); i+=((a)<(b) ? 1 : -1))
#define chmax(a, b) ((a)<(b) ? ((a)=(b), 1) : 0)
#define chmin(a, b) ((a)>(b) ? ((a)=(b), 1) : 0)

template<typename T> using rpriority_queue=priority_queue<T,vector<T>,greater<T>>;
using ll=long long; const int INF=1e9+10; const ll INFL=4e18; using ld=long double; using ull=uint64_t;
using VI=vector<int>; using VVI=vector<VI>; using VL=vector<ll>; using VVL=vector<VL>;
using PL=pair<ll,ll>; using VP=vector<PL>; using WG=vector<vector<pair<int,ll>>>;


// #include"kyopro_library/graph/shortest_path/dijkstra.hpp"

/// @brief 重みなしグラフ g の頂点 start からの最短距離を求める
/// @note O(E+V)
VL BFS(const VVI& g, int start=0){
    int n=g.size();
    VL ret(n,INF); ret[start]=0;
    queue<int> que; que.push(start);

    while(!que.empty()){
        int now=que.front();que.pop();
        for(int nxt:g[now])if(chmin(ret[nxt],ret[now]+1)) que.push(nxt);
    }

    return ret;
}


VL Dijkstra(const WG& g, int start=0){
    int n=g.size();
    VL ret(n,INFL); ret[start]=0;
    rpriority_queue<pair<ll,int>> pq; pq.push({0,start});
    VI seen(n); seen[start]=1;

    while(!pq.empty()){
        auto [tmp,now]=pq.top();pq.pop();
        if(ret[now]<tmp) continue;
        seen[now]=true;
        for(auto [nxt,cost]:g[now])if(!seen[nxt]&&chmin(ret[nxt],ret[now]+cost)) pq.push({ret[nxt],nxt});
    }

    return ret;
}

pair<VI,ll>TreeDiameter(const WG& g){
    VL dist=Dijkstra(g);
    int s=max_element(ALL(dist))-dist.begin();
    dist=Dijkstra(g,s);
    int t=max_element(ALL(dist))-dist.begin();
    VI path;
    int now=t;
    while(now!=s){
        path.push_back(now);
        for(auto[nxt,cost]:g[now]){
            if(dist[now]==dist[nxt]+cost){
                now=nxt;
                break;
            }
        }
    }
    path.push_back(s);
    ll diameter=dist[t];
    return {path,diameter};
}

pair<VI,ll>TreeDiameter(const vector<VI>& g){
    VL dist=BFS(g);
    int s=max_element(ALL(dist))-dist.begin();
    dist=BFS(g,s);
    int t=max_element(ALL(dist))-dist.begin();
    VI path;
    int now=t;
    while(now!=s){
        path.push_back(now);
        for(int nxt:g[now]){
            if(dist[now]==dist[nxt]+1){
                now=nxt;
                break;
            }
        }
    }
    path.push_back(s);
    ll diameter=dist[t];
    return {path,diameter};
}


int main(){
    int N; cin>>N;
    WG 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});
    }

    cout<<TreeDiameter(G).second<<endl;
}