N = int(input())
G = [[] for _ in range(N)]
for i in range(N-1):
    U, V, C = map(int, input().split())
    U -= 1
    V -= 1
    G[U].append((V, C))
    G[V].append((U, C))

p = [-1]*N
pw = [0]*N
child = [[0] for _ in range(N)]

ans = 0


def dfs(v, p):
    global ans
    for u, c in G[v]:
        if u != p:
            child[v].append(dfs(u, v)+c)
    child[v].sort(reverse=True)
    if len(child[v]) >= 2:
        if ans < child[v][0]+child[v][1]:
            ans = child[v][0]+child[v][1]
    return child[v][0]


dfs(0, -1)
print(ans)