from collections import*
(n,),*e=[[*map(int,s.split())]for s in open(0)]
g=[[]for _ in range(n)]
for u,v,w in e:
  g[u-1]+=(v-1,w),
  g[v-1]+=(u-1,w),
def f(g,n,i):
  INF=1<<60
  q=deque([i])
  s=[INF]*n
  s[i]=0
  while q:
    p=q.popleft()
    for v,*c in g[p]:
      nc=c[0] if c else 1
      if s[v]==INF:
        s[v]=s[p]+nc
        q+=v,
  m=max(s)
  q=[i for i in range(n)if s[i]==m]
  return s,q,m
s0,p0,_=f(g,n,0)
ans=0
for i in p0:
  sn,pn,m=f(g,n,i)
  ans=max(ans,m)
print(ans)