"""

真ん中に強すぎる負辺があるとまずい

全方位木dpか？

"""

from collections import deque

N = int(input())

lis = [ [] for i in range(N) ]

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


dp = [float("inf")] * N
plis = [None] * N
q = deque([0])
visit = []
dp[0] = 0

while q:
    v = q.popleft()
    visit.append(v)
    for nex,w in lis[v]:
        if dp[nex] == float("inf"):
            dp[nex] = dp[v] + w
            plis[nex] = v
            q.append(nex)

dps = [i for i in dp]
for v in list(reversed(visit)):
    for nex,w in lis[v]:
        if plis[v] != nex:
            dps[v] = max(dps[v] , dps[nex])


# print (dp,dps)

ans = 0
for v in visit:
    cds = []
    for nex,w in lis[v]:
        if plis[v] != nex:
            cds.append(dps[nex] - dp[v])
    cds.sort()

    # print (cds)

    if len(cds) >= 1:
        ans = max(ans , cds[-1])
    if len(cds) >= 2:
        ans = max(ans , cds[-1] + cds[-2])

print (ans)