import sys
sys.setrecursionlimit(200050)

N = int(input())
E = [[] for _ in range(N)]

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

INF = - 10 ** 10
dp = [INF] * N
def dfs(x, p = -1):
    ret = [0]
    for y,w in E[x]:
        if y != p:
            ret.append(w + dfs(y,x))
    ret.sort(reverse = True)
    if len(ret) == 1:
        dp[x] = ret[0]
    else:
        dp[x] = sum(ret[:2])
    return ret[0]

dfs(0)
print(max(dp))