#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <set>
#include <cmath>
#include <iomanip>
#include <stack>
#include <queue>
#include <bitset>
#include <tuple>
#include <map>
#include <functional>

#define fi first
#define se second
#define rep(i,n) for(ll i=0;i<(n);i++)
#define rrep(i,n) for(ll i=(n)-1;i>=0;i--)
#define orep(i,n) for(ll i=1;i<=(n);i++)

#define nfor(i,s,n) for(ll i=(s);i<(n);i++)
#define dfor(i,s,n) for(ll i=(s)-1;i>=n;i--)
#define INF 9e18//9223372036854775807

#define all(a)  a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()

#define chmax(x,y) x = max(x,y)
#define chmin(x,y) x = min(x,y)

#define pb push_back
#define pob pop_back

#define vc vector

#define YES cout << "Yes" << endl;
#define NO cout << "No" << endl;
#define YN {cout << "Yes" << endl;}else{cout << "No" << endl;}
#define dame cout << -1 << endl;

#define vc_unique(v) v.erase(unique(v.begin(), v.end()), v.end())
#define vc_rotate(v) rotate(v.begin(), v.begin()+1, v.end())

#define pop_cnt(s) ll(popcount(uint64_t(s)))
#define next_p(v) next_permutation(v.begin(),v.end())

#ifndef ONLINE_JUDGE
#define _GLIBCXX_DEBUG
#endif

using namespace std;
using ll = long long;
using ld = long double;
using pll = pair<ll,ll>;
using vvl = vector<vector<ll>>;
using vl = vector<ll>;
using Graph = vector<vector<ll>>;

template<class T> using pq = priority_queue<T,vc<T>,less<T>>;
template<class T> using pq_g = priority_queue<T,vc<T>,greater<T>>;

vl dx = {0,1,0,-1};//vl dx = {1,1,0,-1,-1,-1,0,1};
vl dy = {1,0,-1,0};//vl dy = {0,1,1,1,0,-1,-1,-1};

bool out_grid(ll i, ll j, ll h, ll w){//trueならcontinueする
	return(!(0 <= i && i < h && 0 <= j && j<w));
}

void print(ld x){printf("%.20Lf\n", x);}

//////////////////////////////////////////////////////////////////
vl dist;
vector<vector<pair<ll,ll>>> UVW;

void dfs(ll v){
	for(auto [nv,w] : UVW[v]){
		if(dist[nv] != -INF)continue;
		dist[nv] = dist[v] + w;
		dfs(nv);
	}
}

int main(){
	ll N;
	cin >> N;
	
	UVW.resize(N);
	dist.resize(N);

	rep(i,N-1){
		ll tmp1,tmp2,tmp3;
		cin >> tmp1 >> tmp2 >> tmp3;
		UVW[tmp1-1].pb({tmp2-1,tmp3});
		UVW[tmp2-1].pb({tmp1-1,tmp3});
	}

	rep(i,N){
		dist[i] = -INF;
	}

	dist[0] = 0;

	dfs(0);

	ll av = 0;

	rep(i,N){
		if(dist[av] <= dist[i])av = i;
	}

	rep(i,N){
		dist[i] = -INF;
	}

	dist[av] = 0;

	dfs(av);

	rep(i,N){
		if(dist[av] <= dist[i])av = i;
	}

	cout << dist[av] <<endl;

}