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]+=[(v,w)]
  e[v]+=[(u,w)]
X=10**20
u=[[0,-X] for _ in range(n)]
v=[0]*n
q=[0]
while len(q):
  s=q[-1]
  if v[s]==0:
    v[s]=1
    for t,c in e[s]:
      if v[t]==0:
        q+=[t]
  else:
    for t,c in e[s]:
      if v[t]==0:
        u[s]+=[u[t][0]+c]
        u[s]=(sorted(u[s])[-2:])[::-1]
    v[s]=0
    q.pop()
v=[0]*n
q=[0]
while len(q):
  s=q[-1]
  if v[s]==0:
    v[s]=1
    for t,c in e[s]:
      if v[t]==0:
        q+=[t]
        u[t]+=[u[s][u[s][0]==u[t][0]+c]+c]
        u[t]=(sorted(u[t])[-2:])[::-1]
  else:
    v[s]=0
    q.pop()
print(max(u[s][0]+u[s][1]*(len(e[s])>1) for s in range(n)))