import java.io.*;
import java.util.HashMap;
import java.util.Map;

class Main{
    static BufferedReader read = new BufferedReader(new InputStreamReader(System.in));
    static int N = 10010;
    static int ans = 0;
    static Map<Integer, Map<Integer, Integer>> graph = new HashMap(N);
    public static void add(int a, int b, int c){
        graph.putIfAbsent(a, new HashMap());
        graph.get(a).put(b, c);
    }

    public static void main(String[] args) throws Exception{
        int n = Integer.valueOf(read.readLine());
        for(int i = 1; i < n; i++){
            String[] ss = read.readLine().split(" ");
            int a = Integer.valueOf(ss[0]);
            int b = Integer.valueOf(ss[1]);
            int c = Integer.valueOf(ss[2]);
            add(a, b, c); add(b, a, c);
        }
        dfs(1, -1);
        System.out.println(ans);
    }

    public static int dfs(int root, int father){
        int p1 = 0, p2 = 0;
        for(Integer j: graph.get(root).keySet()){
            //如果是父节点， 则不走
            if(j == father) continue;
            int cld = dfs(j, root) + graph.get(root).get(j);
            if(cld >= p1){
                p2 = p1; p1 = cld;
            }else if(cld > p2) p2 = cld;
        }
        ans = Math.max(ans, p1 + p2);
        return p1;
    }
}