from heapq import heappush, heappop

INF = 10 ** 18

def dijkstra(s, N): # (始点, ノード数)
    dist = [INF for _ in range(N)]
    hq = [(0, s)]
    dist[s] = 0
    seen = [0] * N # ノードが確定済みかどうか
    while hq:
        d, v = heappop(hq) # ノードを pop する
        if seen[v]:
            continue
        seen[v] = 1
        for to, cost in G[v]: # ノード v に隣接しているノードに対して
            if dist[v] + cost < dist[to]:
                dist[to] = dist[v] + cost
                heappush(hq, (dist[to], to))
    return dist

import sys
input = sys.stdin.readline
N = int(input())
G = [[] for _ in range(N)]
for _ in range(N-1):
    u, v, w = map(int, input().split())
    u-=1
    v-=1
    G[u].append((v, w))
    G[v].append((u, w))
dist = dijkstra(0, N)
ma = -INF
idx = -1
for i, d in enumerate(dist):
    if ma<d:
        idx = i
dist2 = dijkstra(idx, N)
ans = 0
for d in dist2:
    ans = max(ans, d)
print(ans)