N = int(input())

connected = [[] for _ in range(N)]

for i in range(N-1):
	a,b,w = map(int,input().split())
	a -= 1
	b -= 1
	connected[a].append((b,w))
	connected[b].append((a,w))

dist = [-1]*N
dist[0] = 0

stack = [0]

while stack:
	v = stack.pop()
	for u,w in connected[v]:
		if dist[u] == -1:
			dist[u] = w + dist[v]
			stack.append(u)

Mi = -1
M = -1
for i in range(N):
	if dist[i] > M:
		Mi = i
		M = dist[i]
		
#print(dist)

dist_ = [-1]*N
dist_[Mi] = 0

stack = [Mi]

while stack:
	v = stack.pop()
	for u,w in connected[v]:
		if dist_[u] == -1:
			dist_[u] = w + dist_[v]
			stack.append(u)

#print(dist_)
print(max(dist_))