from collections import defaultdict
N=int(input())
G=[[] for _ in range(N)]
D=defaultdict(int)
for _ in range(N-1):
    u,v,w=map(int,input().split())
    u-=1;v-=1
    G[u].append(v)
    G[v].append(u)
    D[(u,v)]=w
    D[(v,u)]=w
A=[(0,0) for _ in range(N)]
vis=[0 for _ in range(N)]
def dfs(now):
    vis[now]=1
    for nxt in G[now]:
        if vis[nxt]:continue
        dfs(nxt)
        if A[nxt][0]+D[(now,nxt)]>A[now][0]:A[now]=(A[nxt][0]+D[(now,nxt)],nxt)
dfs(0)
B=[0 for _ in range(N)]
vis=[0 for _ in range(N)]
def dfs2(now):
    vis[now]=1
    if A[now][0]>B[now]:B[now]=A[now][0]
    for nxt in G[now]:
        if nxt==A[now][1]:continue
        if A[now][0]+D[(now,nxt)]>B[now]:B[now]=A[now][0]+D[(now,nxt)]
dfs2(0)
print(max(B))