from collections import defaultdict, deque

# bfs to bfs 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 bfs(start):
    dist = [-1] * (n + 1)
    dist[start] = 0
    queue = deque([start])
    while queue:
        node = queue.popleft()
        for neighbor, weight in graph[node]:
            if dist[neighbor] == -1:
                dist[neighbor] = dist[node] + weight
                queue.append(neighbor)
    farthest_node = dist.index(max(dist))
    return farthest_node, dist[farthest_node]


u, _ = bfs(1)
_, diameter = bfs(u)

print(diameter)