# 重み付き木の直径を求める
from collections import deque
N = int(input())

edges = [[] for _ in range(N)]
for _ in range(N - 1):
    a, b, c = map(int, input().split())
    edges[a - 1].append((b - 1, c))
    edges[b - 1].append((a - 1, c))

def dfs(start, edges):
    dist = [-1] * len(edges)
    dist[start] = 0
    queue = deque([start])
    max_dist = -10**9-1
    max_node = start
    
    while queue:
        node = queue.popleft()
        for neighbor, weight in edges[node]:
            if dist[neighbor] == -1:
                dist[neighbor] = dist[node] + weight
                queue.append(neighbor)
                if dist[neighbor] > max_dist:
                    max_dist = dist[neighbor]
                    max_node = neighbor
    
    return max_node, max_dist


farthest_node, _ = dfs(0, edges)
_, diameter = dfs(farthest_node, edges)

print(diameter)