from collections import defaultdict, deque


def tree_diameter_with_weight(n: int, adj: defaultdict) -> tuple[int, list]:
    def bfs(start):
        q = deque([start])
        dists = [-1] * n
        dists[start] = 0
        while q:
            v = q.popleft()
            for to, w in adj[v]:
                if dists[to] != -1: continue
                dists[to] = dists[v] + w
                q.append(to)

        return dists

    dists = bfs(0)
    _, ai = max((d, i) for i, d in enumerate(dists))
    dists = bfs(ai)
    d, bi = max((d, i) for i, d in enumerate(dists))
    path = [(bi, d)]  # (頂点番号, 距離)
    while path[-1][1] > 0:
        v, s = path[-1]
        for to, w in adj[v]:
            if dists[to] == s - w:
                path.append((to, s - w))
                break
        else:
            assert False

    return d, [v for v, _ in path]


N = int(input())
adj = defaultdict(list)
max_w = 0
for _ in range(N-1):
    u, v, w = map(int, input().split())
    u -= 1
    v -= 1
    adj[u].append((v, w))
    adj[v].append((u, w))
    max_w = max(max_w, w)

d, _ = tree_diameter_with_weight(N, adj)
ans = max(d, max_w)
print(ans)