import sys
sys.setrecursionlimit(10**6)
N = int(input())
G = {i:[] for i in range(1,N+1)}
for _ in range(N-1):
    u,v,w = map(int,input().split())
    G[u].append((v,w))
    G[v].append((u,w))
dp = [0]*(N+1)
Pa = [0]*(N+1)
def dfs(v,par):
    for u,w in G[v]:
        if u!=par:
            Pa[u] = v
            dfs(u,v)
            dp[v] = max(dp[v],dp[u]+w)
dfs(1,0)
ans = 0
for v in range(1,N+1):
    A = []
    for u,w in G[v]:
        if u!=Pa[v]:
            A.append(max(0,dp[u]+w))
    A = sorted(A,reverse=True)
    if len(A)>1:
        ans = max(ans,A[0]+A[1])
    elif len(A)==1:
        ans = max(ans,A[0])
print(ans)