N = int(input())
edge = [[] for _ in range(N)]
for _ in range(N-1):
    u,v,w = list(map(int,input().split()))
    u -= 1;v -= 1
    edge[u].append((v,w))
    edge[v].append((u,w))

from collections import deque
def bfs(s):
    dist = [None]*N
    que = deque([s])
    dist[s] = 0
    while que:
        v = que.popleft()
        d = dist[v]
        for w, c in edge[v]:
            if dist[w] is not None:
                continue
            dist[w] = d + c
            que.append(w)
    d = max(dist)
    return dist.index(d), d
u, _ = bfs(0)
v, d = bfs(u)

print(d)