import sys input = sys.stdin.buffer.readline class UnionFind: def __init__(self, n): self.parent = [-1] * n self.n = n self.cnt = n def root(self, x): if self.parent[x] < 0: return x else: self.parent[x] = self.root(self.parent[x]) return self.parent[x] def merge(self, x, y): x = self.root(x) y = self.root(y) if x == y: return False if self.parent[x] > self.parent[y]: x, y = y, x self.parent[x] += self.parent[y] self.parent[y] = x self.cnt -= 1 return True def same(self, x, y): return self.root(x) == self.root(y) def size(self, x): return -self.parent[self.root(x)] def count(self): return self.cnt def groups(self): res = [[] for _ in range(self.n)] for i in range(self.n): res[self.root(i)].append(i) return [group for group in res if group] def rerooting(n, edges, unit, merge, addnode): tree = [[] for i in range(n)] idxs = [[] for i in range(n)] for u, v in edges: idxs[u].append(len(tree[v])) idxs[v].append(len(tree[u])) tree[u].append(v) tree[v].append(u) sub = [[unit] * len(tree[v]) for v in range(n)] noderes = [unit] * n # topological sort tp_order = [] par = [-1] * n for root in range(n): if par[root] != -1: continue stack = [root] while stack: v = stack.pop() tp_order.append(v) for nxt_v in tree[v]: if nxt_v == par[v]: continue par[nxt_v] = v stack.append(nxt_v) # tree DP for v in reversed(tp_order[1:]): res = unit par_idx = -1 for idx, nxt_v in enumerate(tree[v]): if nxt_v == par[v]: par_idx = idx continue res = merge(res, sub[v][idx]) if par_idx != -1: sub[par[v]][idxs[v][par_idx]] = addnode(res, v) # rerooting DP for v in tp_order: acc_back = [unit] * len(tree[v]) for i in reversed(range(1, len(acc_back))): acc_back[i - 1] = merge(sub[v][i], acc_back[i]) acc_front = unit for idx, nxt_v in enumerate(tree[v]): res = addnode(merge(acc_front, acc_back[idx]), v) sub[nxt_v][idxs[v][idx]] = res acc_front = merge(acc_front, sub[v][idx]) noderes[v] = addnode(acc_front, v) return sub return noderes n = int(input()) edges = [list(map(int, input().split())) for _ in range(n - 1)] es = [] tree = [[] for i in range(n)] max_cost = 0 for u, v, cost in edges: u -= 1 v -= 1 max_cost = max(max_cost, cost) es.append((u, v)) tree[u].append((v, cost)) tree[v].append((u, cost)) vals = [0] * n for u, v, cost in edges: u -= 1 v -= 1 if cost == max_cost: vals[u] = 1 vals[v] = 1 unit = 0 merge = lambda a, b: a + b addnode = lambda val, v: val + vals[v] sub = rerooting(n, es, unit, merge, addnode) for v, res in enumerate(sub): if len(res) <= 1: continue res = sorted(res, reverse=True) if res[1] != 0: vals[v] = 1 is_path = True ends = [] for v in range(n): if vals[v] == 0: continue cnt = 0 for nxt_v, cost in tree[v]: if vals[nxt_v] >= 1: cnt += 1 if cnt > 2: is_path = False if cnt == 1: ends.append(v) if not is_path: print(max_cost) exit() else: print(re)