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))

dist = [0] * N
def dfs(v, p):
    for u, w in G[v]:
        if u == p:
            continue
        dist[u] = dist[v] + w
        dfs(u, v)
dfs(0, -1)

leaf = [i for i in range(N) if len(G[i]) == 1]
leaf.sort(key=lambda x: dist[x], reverse=True)
v = leaf[0]
dist = [0] * N
dfs(v, -1)
print(max(dist))