def dist(g: list[list[int]], s: int) -> tuple[list[int], list[int]]:
    n = len(g)
    visited = [False] * n
    visited[s] = True
    d = [0] * n
    stk = [(s, 0)]
    while stk:
        v, p = stk.pop()
        for nv, q in g[v]:
            if not visited[nv]:
                visited[nv] = True
                d[nv] = p + q
                stk.append((nv, p + q))
    return d


N = int(input())
G = [[] for _ in range(N)]
for _ in range(N - 1):
    a, b, c = map(int, input().split())
    G[a - 1].append((b - 1, c))
    G[b - 1].append((a - 1, c))
dists = dist(G, 0)
print(max(dist(G, dists.index(max(dists)))))