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

ans = 0

def dfs(v, p):
    global ans
    res = [0, 0]
    for u, w in G[v]:
        if u == p:
            continue
        res.append(dfs(u, v) + w)
    res.sort(reverse=True)
    ans = max(ans, res[0] + res[1], res[0])
    return res[0]

dfs(0, -1)
print(ans)