from collections import deque


def bfs(s):
    dq = deque()
    dq.append([s, 0])
    dist = [10**9 for _ in range(N)]
    dist[s] = 0
    res = []
    while len(dq) != 0:
        p, h = dq.popleft()
        res.append(p)
        for e,_ in edge[p]:
            if dist[e] == 10**9:
                dq.append([e, h + 1])
                dist[e] = h + 1
    return res

N=int(input())
edge = [[] for _ in range(N)]
for _ in range(N-1):
    u,v,w=map(int,input().split())
    edge[u-1].append([v-1,w])
    edge[v-1].append([u-1,w])
res = bfs(0)
tans=[-1]*N
ans=0
for r in res[::-1]:
    d=[0,0]
    for e,w in edge[r]:
        if tans[e] == -1:
            continue
        d.append(tans[e]+w)
    d.sort(reverse=True)
    tans[r]=d[0]
    ans=max(ans,d[0]+d[1])
print(ans)