mod = 1000000007 eps = 10**-9 def main(): import sys from heapq import heappush, heappop input = sys.stdin.buffer.readline class SegmentTree: def __init__(self, A, initialize=True, segfunc=max, ident=-20000000000): self.N = len(A) self.LV = (self.N - 1).bit_length() self.N0 = 1 << self.LV self.segfunc = segfunc self.ident = ident if initialize: self.data = [self.ident] * self.N0 + A + [self.ident] * (self.N0 - self.N) for i in range(self.N0 - 1, 0, -1): self.data[i] = segfunc(self.data[i * 2], self.data[i * 2 + 1]) else: self.data = [self.ident] * (self.N0 * 2) def update(self, i, x): i += self.N0 - 1 self.data[i] = x for _ in range(self.LV): i >>= 1 self.data[i] = self.segfunc(self.data[i * 2], self.data[i * 2 + 1]) def get(self, i): return self.data[i + self.N0 - 1] # open interval [l, r) def query(self, l, r): l += self.N0 - 1 r += self.N0 - 1 ret_l = self.ident ret_r = self.ident while l < r: if l & 1: ret_l = self.segfunc(ret_l, self.data[l]) l += 1 if r & 1: ret_r = self.segfunc(self.data[r - 1], ret_r) r -= 1 l >>= 1 r >>= 1 return self.segfunc(ret_l, ret_r) # return smallest i(l <= i < r) s.t. check(A[i]) == True def binsearch(self, l, r, check): if not check(self.query(l, r)): return r l += self.N0 - 1 val = self.ident while True: if check(self.segfunc(val, self.data[l])): break if l & 1: val = self.segfunc(val, self.data[l]) l += 1 l >>= 1 while l < self.N0: newval = self.segfunc(val, self.data[l * 2]) if not check(newval): val = newval l = (l << 1) + 1 else: l <<= 1 return l - self.N0 + 1 N = int(input()) adj = [[] for _ in range(N+1)] C = [] CC = [] E = {} for i in range(N - 1): a, b, c = map(int, input().split()) adj[a].append((b, c)) adj[b].append((a, c)) C.append((c, i+1, a, b)) CC.append(c) E[a * (N + 1) + b] = i + 1 E[b * (N + 1) + a] = i + 1 C.sort(key=lambda x: x[0], reverse=True) ma = C[0][0] v_left = C[0][2] v_right = C[0][3] ST = SegmentTree(CC) ST.update(C[0][1], 0) seen = [0] * (N+1) seen[v_left] = 1 seen[v_right] = 1 pq = [] par = [-1] * (N+1) for u, c in adj[v_left]: if not seen[u]: heappush(pq, (-c, u, 0)) par[u] = v_left for u, c in adj[v_right]: if not seen[u]: heappush(pq, (-c, u, 1)) par[u] = v_right ans = ST.query(1, N) while pq: c, v, flg = heappop(pq) c *= -1 if flg == 0: if par[v] != v_left: continue i = E[v_left * (N + 1) + v] else: if par[v] != v_right: continue i = E[v_right * (N + 1) + v] ST.update(i, 0) ans = min(ans, max(ST.query(1, N), ma - c)) seen[v] = 1 if flg == 0: v_left = v for u, cc in adj[v]: if not seen[u]: heappush(pq, (-cc, u, 0)) par[u] = v else: v_right = v for u, cc in adj[v]: if not seen[u]: heappush(pq, (-cc, u, 1)) par[u] = v print(ans) if __name__ == '__main__': main()