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))

mx_cst = mx_idx = 0
stk = [(0, -1, 0)]
while stk:
  c, p, d = stk.pop()
  if mx_cst < d:
    mx_cst = d
    mx_idx = c
  for t, w in es[c]:
    if t == p: continue
    stk.append((t, c, max(0, d+w)))

mx_cst1 = mx_idx1 = 0
stk = [(mx_idx, -1, 0)]
while stk:
  c, p, d = stk.pop()
  if mx_cst1 < d:
    mx_cst1 = d
    mx_idx1 = c
  for t, w in es[c]:
    if t == p: continue
    stk.append((t, c, max(0, d+w)))

print(mx_cst1)