from collections import defaultdict

import sys

sys.setrecursionlimit(10**6)

# dfs to dfs で最長距離を求める

n = int(input())
graph = defaultdict(list)
for _ in range(n - 1):
    u, v, w = map(int, input().split())
    graph[u].append((v, w))
    graph[v].append((u, w))


def dfs(node, parent):
    far_node = node
    max_dist = -float("inf")
    for neighbor, weight in graph[node]:
        if neighbor == parent:
            continue
        n_node, n_dist = dfs(neighbor, node)
        n_dist += weight
        if n_dist > max_dist:
            max_dist = n_dist
            far_node = n_node
    return far_node, max_dist if max_dist != -float("inf") else 0


u, _ = dfs(1, -1)
v, diameter = dfs(u, -1)

print(diameter)