import sys
sys.setrecursionlimit(10**7)

def solve():
    input = sys.stdin.readline
    N = int(input())
    graph = [[] for _ in range(N+1)]
    for _ in range(N-1):
        u, v, w = map(int, input().split())
        graph[u].append((v, w))
        graph[v].append((u, w))

    def dfs(u, parent, dist):
        far_node, far_dist = u, dist
        for v, w in graph[u]:
            if v == parent: continue
            cand_node, cand_dist = dfs(v, u, dist + w)
            if cand_dist > far_dist:
                far_node, far_dist = cand_node, cand_dist
        return far_node, far_dist

    A, _ = dfs(1, 0, 0)
    _, diam = dfs(A, 0, 0)

    print(max(0, diam))

if __name__ == "__main__":
    solve()