import bisect
import sys
from math import isqrt
from typing import List, Tuple

sys.setrecursionlimit(10 ** 6)

MOD = 998244353

int1 = lambda x: int(x) - 1
input = lambda: sys.stdin.readline().rstrip('\n')
ii = lambda: int(input())
vi = lambda: list(map(int, input().split()))
vi1 = lambda: list(map(int1, input().split()))


def dbg(*args, **kwargs):
    print(*(repr(arg) for arg in args), *(f'{k}: {repr(v)}' for k, v in kwargs.items()),
          sep='; ', file=sys.stderr, flush=True)


def main():
    n = ii()
    g = [[] for _ in range(n)]
    for _ in range(n - 1):
        u, v, w = vi()
        g[u - 1].append((v - 1, w))
        g[v - 1].append((u - 1, w))

    def dfs(a, p):
        ans = 0
        tp = [0, 0]
        for u, w in g[a]:
            if u == p:
                continue
            aa, tt = dfs(u, a)
            ans = max(ans, aa)
            nxt = [i + w for i in tt]
            for i in tp:
                for j in nxt:
                    ans = max(ans, i + j)
            tp.extend(nxt)
            tp.sort(reverse=True)
            tp = tp[:2]
        return ans, tp[:2]

    a, _ = dfs(0, None)

    return a


def _start():
    if (ret := main()) is not None:
        print(*ret) if isinstance(ret, List) or isinstance(ret, Tuple) else print(ret)


if __name__ == '__main__':
    _start()