import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################

n = ni()
g = [[] for i in range(n)]

for _ in range(n-1):
    u, v, w = na()
    u -= 1
    v -= 1
    g[u].append((v, w))
    g[v].append((u, w))

et = []
q = [0]
seen  = [0] * n
seen[0] = 1
p = [-1] * n
w = [-1] * n

while q:
    x = q.pop()
    et.append(x)
    for y, i in g[x]:
        if seen[y]:continue
        q.append(y)
        seen[y] = 1
        p[y] = x
        w[y] = i
inf = 10 ** 18
dp0 = [0] * n
dp1 = [-inf] * n
for v in et[1:][::-1]:
    dp1[p[v]] = max(dp1[p[v]], dp0[v] + w[v] + dp0[p[v]])
    dp0[p[v]] = max(dp0[p[v]], dp0[v] + w[v])

# print(dp0, dp1)
print(max([0] + dp1))