// -*- coding:utf-8-unix -*- // #![feature(map_first_last)] #![allow(dead_code)] #![allow(unused_imports)] #![allow(unused_macros)] use std::any::Any; use std::cmp::Ordering::*; use std::collections::*; use std::convert::*; use std::convert::{From, Into}; use std::error::Error; use std::f64::consts::PI; use std::fmt::Debug; use std::fmt::Display; use std::fs::File; use std::hash::Hash; use std::io::prelude::*; use std::io::*; use std::iter::Filter; use std::marker::Copy; use std::mem::*; use std::ops::Bound::*; use std::ops::RangeBounds; use std::ops::{Add, Mul, Neg, Sub}; use std::slice::from_raw_parts; use std::str; use std::vec; const INF: i64 = 1223372036854775807; const UINF: usize = INF as usize; // const FINF: f64 = 122337203685.0; const LINF: i64 = 2147483647; const FINF: f64 = LINF as f64; const INF128: i128 = 1223372036854775807000000000000; const MOD: i64 = 1000000007; // const MOD: i64 = 998244353; const MPI: f64 = 3.14159265358979323846264338327950288f64; // const MOD: i64 = INF; const UMOD: usize = MOD as usize; use std::cmp::*; use std::collections::*; use std::io::stdin; use std::io::stdout; use std::io::Write; macro_rules! p { ($x:expr) => { println!("{}", $x); }; } macro_rules! d { ($x:expr) => { println!("{:?}", $x); }; } // use str::Chars; // use str::Chars; #[allow(dead_code)] fn read() -> T { let mut s = String::new(); std::io::stdin().read_line(&mut s).ok(); s.trim().parse().ok().unwrap() } #[allow(dead_code)] fn readi() -> (i64) { let mut str = String::new(); let _ = stdin().read_line(&mut str).unwrap(); let mut iter = str.split_whitespace(); iter.next().unwrap().parse::().unwrap() } #[allow(dead_code)] fn read_vec() -> Vec { read::() .split_whitespace() .map(|e| e.parse().ok().unwrap()) .collect() } #[allow(dead_code)] fn read_mat(n: u32) -> Vec> { (0..n).map(|_| read_vec()).collect() } #[allow(dead_code)] fn readii() -> (i64, i64) { let mut str = String::new(); let _ = stdin().read_line(&mut str).unwrap(); let mut iter = str.split_whitespace(); ( iter.next().unwrap().parse::().unwrap(), iter.next().unwrap().parse::().unwrap(), ) } fn readff() -> (f64, f64) { let mut str = String::new(); let _ = stdin().read_line(&mut str).unwrap(); let mut iter = str.split_whitespace(); ( iter.next().unwrap().parse::().unwrap(), iter.next().unwrap().parse::().unwrap(), ) } #[allow(dead_code)] fn readiii() -> (i64, i64, i64) { let mut str = String::new(); let _ = stdin().read_line(&mut str).unwrap(); let mut iter = str.split_whitespace(); ( iter.next().unwrap().parse::().unwrap(), iter.next().unwrap().parse::().unwrap(), iter.next().unwrap().parse::().unwrap(), ) } #[allow(dead_code)] fn readuu() -> (usize, usize) { let mut str = String::new(); let _ = stdin().read_line(&mut str).unwrap(); let mut iter = str.split_whitespace(); ( iter.next().unwrap().parse::().unwrap(), iter.next().unwrap().parse::().unwrap(), ) } fn readcc() -> (char, char) { let mut str = String::new(); let _ = stdin().read_line(&mut str).unwrap(); let mut iter = str.split_whitespace(); ( iter.next().unwrap().parse::().unwrap(), iter.next().unwrap().parse::().unwrap(), ) } fn readuuu() -> (usize, usize, usize) { let mut str = String::new(); let _ = stdin().read_line(&mut str).unwrap(); let mut iter = str.split_whitespace(); ( iter.next().unwrap().parse::().unwrap(), iter.next().unwrap().parse::().unwrap(), iter.next().unwrap().parse::().unwrap(), ) } #[allow(dead_code)] fn readiiii() -> (i64, i64, i64, i64) { let mut str = String::new(); let _ = stdin().read_line(&mut str).unwrap(); let mut iter = str.split_whitespace(); ( iter.next().unwrap().parse::().unwrap(), iter.next().unwrap().parse::().unwrap(), iter.next().unwrap().parse::().unwrap(), iter.next().unwrap().parse::().unwrap(), ) } #[allow(dead_code)] fn readuuuu() -> (usize, usize, usize, usize) { let mut str = String::new(); let _ = stdin().read_line(&mut str).unwrap(); let mut iter = str.split_whitespace(); ( iter.next().unwrap().parse::().unwrap(), iter.next().unwrap().parse::().unwrap(), iter.next().unwrap().parse::().unwrap(), iter.next().unwrap().parse::().unwrap(), ) } macro_rules! M { (a :expr ) => { M::new({ a }) }; } #[derive(Copy, Clone, Debug)] pub struct M(i64); impl M { fn new(x: i64) -> Self { M(x.rem_euclid(MOD)) } fn pow(self, n: usize) -> Self { match n { 0 => M::new(1), _ => { let mut a = self.pow(n >> 1); a *= a; if n & 1 == 1 { a *= self; } a } } } fn inv(self) -> Self { self.pow((MOD - 2) as usize) } } impl std::ops::Neg for M { type Output = M; fn neg(self) -> Self::Output { Self::new(-self.0) } } impl std::ops::AddAssign for M { fn add_assign(&mut self, rhs: Self) { self.0 += rhs.0; self.0 %= MOD; } } impl std::ops::AddAssign for M { fn add_assign(&mut self, rhs: i64) { *self += M::new(rhs); } } impl std::ops::AddAssign for M { fn add_assign(&mut self, rhs: usize) { *self += M::new(rhs as i64); } } impl std::ops::Add for M where M: std::ops::AddAssign, { type Output = Self; fn add(self, other: T) -> Self { let mut res = self; res += other; res } } impl std::ops::SubAssign for M { fn sub_assign(&mut self, rhs: Self) { self.0 -= rhs.0; if self.0 < 0 { self.0 += MOD; } } } impl std::ops::SubAssign for M { fn sub_assign(&mut self, rhs: i64) { *self -= M::new(rhs); if (*self).0 < 0 { self.0 += MOD; } } } impl std::ops::SubAssign for M { fn sub_assign(&mut self, rhs: usize) { *self -= M::new(rhs as i64); if (*self).0 < 0 { self.0 += MOD; } } } impl std::ops::Sub for M where M: std::ops::SubAssign, { type Output = Self; fn sub(self, other: T) -> Self { let mut res = self; res -= other; res } } impl std::ops::MulAssign for M { fn mul_assign(&mut self, rhs: Self) { self.0 %= MOD; self.0 *= (rhs.0 % MOD); self.0 %= MOD; } } impl std::ops::MulAssign for M { fn mul_assign(&mut self, rhs: i64) { *self *= M::new(rhs); } } impl std::ops::MulAssign for M { fn mul_assign(&mut self, rhs: usize) { *self *= M::new(rhs as i64); } } impl std::ops::Mul for M where M: std::ops::MulAssign, { type Output = Self; fn mul(self, other: T) -> Self { let mut res = self; res *= other; res } } impl std::ops::DivAssign for M { fn div_assign(&mut self, rhs: Self) { *self *= rhs.inv(); } } impl std::ops::DivAssign for M { fn div_assign(&mut self, rhs: i64) { *self /= M::new(rhs); } } impl std::ops::DivAssign for M { fn div_assign(&mut self, rhs: usize) { *self /= M::new(rhs as i64); } } impl std::ops::Div for M where M: std::ops::DivAssign, { type Output = Self; fn div(self, other: T) -> Self { let mut res = self; res /= other; res } } impl std::fmt::Display for M { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { write!(f, "{}", self.0) } } impl std::ops::Deref for M { type Target = i64; fn deref(&self) -> &Self::Target { &self.0 } } impl std::ops::DerefMut for M { fn deref_mut(&mut self) -> &mut Self::Target { &mut self.0 } } #[allow(dead_code)] pub fn gcd(a: usize, b: usize) -> usize { if b == 0 { a } else { gcd(b, a % b) } } #[allow(dead_code)] pub fn lcm(a: usize, b: usize) -> usize { a / gcd(a, b) * b } #[allow(dead_code)] /// (gcd, x, y) pub fn extgcd(a: i64, b: i64) -> (i64, i64, i64) { if b == 0 { (a, 1, 0) } else { let (gcd, x, y) = extgcd(b, a % b); (gcd, y, x - (a / b) * y) } } #[allow(dead_code)] /// x ^ n % m pub fn mod_pow(x: usize, n: usize, m: usize) -> usize { let mut res = 1; let mut x = x % m; let mut n = n; while n > 0 { if n & 1 == 1 { res = (res * x) % m; } x = (x * x) % m; n >>= 1; } res } pub struct Dsu { n: usize, // root node: -1 * component size // otherwise: parent parent_or_size: Vec, } impl Dsu { // 0 <= size <= 10^8 is constrained. pub fn new(size: usize) -> Self { Self { n: size, parent_or_size: vec![-1; size], } } pub fn merge(&mut self, a: usize, b: usize) -> usize { assert!(a < self.n); assert!(b < self.n); let (mut x, mut y) = (self.leader(a), self.leader(b)); if x == y { return x; } if -self.parent_or_size[x] < -self.parent_or_size[y] { std::mem::swap(&mut x, &mut y); } self.parent_or_size[x] += self.parent_or_size[y]; self.parent_or_size[y] = x as i32; x } pub fn same(&mut self, a: usize, b: usize) -> bool { assert!(a < self.n); assert!(b < self.n); self.leader(a) == self.leader(b) } pub fn leader(&mut self, a: usize) -> usize { assert!(a < self.n); if self.parent_or_size[a] < 0 { return a; } self.parent_or_size[a] = self.leader(self.parent_or_size[a] as usize) as i32; self.parent_or_size[a] as usize } pub fn size(&mut self, a: usize) -> usize { assert!(a < self.n); let x = self.leader(a); -self.parent_or_size[x] as usize } pub fn groups(&mut self) -> Vec> { let mut leader_buf = vec![0; self.n]; let mut group_size = vec![0; self.n]; for i in 0..self.n { leader_buf[i] = self.leader(i); group_size[leader_buf[i]] += 1; } let mut result = vec![Vec::new(); self.n]; for i in 0..self.n { result[i].reserve(group_size[i]); } for i in 0..self.n { result[leader_buf[i]].push(i); } result .into_iter() .filter(|x| !x.is_empty()) .collect::>>() } } fn solve() { let n: usize = read(); let mut vp = vec![]; for i in 0..n - 1 { let p = readuuu(); vp.push((p.2, p.0 - 1, p.1 - 1)); } vp.sort(); vp.reverse(); let mut res = vp[0].0; let mut dec = 0; let mut la = vp[0].1; let mut lb = vp[0].2; for i in 1..n - 1 { let (c, a, b) = vp[i]; if la == a || la == b || lb == a || lb == b { if la == a { la = b; } else if la == b { la = a; } else if lb == a { lb = b; } else if lb == b { lb = a; } if res - c > c { break; } dec = c; } else { p!(c); return; } // d!((la, lb)); } res -= dec; p!(res); return; } fn main() { solve(); }