import sys
sys.setrecursionlimit(5*10**5)
import pypyjit
pypyjit.set_param('max_unroll_recursion=0')

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

def tree_dp(c, p):
  dp0 = dp1 = 0
  for t, w in es[c]:
    if t == p: continue
    
    pdp0, pdp1 = tree_dp(t, c)
    ndp0 = ndp1 = 0
    
    ndp0 = max(dp0, pdp0+w)
    ndp1 = max(dp1, pdp1, dp0+pdp0+w)
    
    dp0, dp1 = ndp0, ndp1
  
  return dp0, dp1

dp0, dp1 = tree_dp(0, -1)
ans = max(dp0, dp1)
print(ans)