// -*- coding:utf-8-unix -*- // #![feature(map_first_last)] #![allow(dead_code)] #![allow(unused_imports)] #![allow(unused_macros)] use std::collections::*; use std::convert::*; use std::convert::{From, Into}; use std::fmt::Debug; use std::fs::File; use std::io::prelude::*; use std::io::*; use std::marker::Copy; use std::mem::*; use std::ops::Bound::*; use std::ops::{Add, Mul, Neg, Sub}; use std::str; use std::vec; use std::{cmp, process::Output}; use std::{cmp::Ordering, env::consts::DLL_PREFIX}; use std::{cmp::Ordering::*, f32::consts::PI}; const INF: i64 = 1223372036854775807; const UINF: usize = INF as usize; const FINF: f64 = 122337203685.0; const INF128: i128 = 1223372036854775807000000000000; const LINF: i64 = 2147483647; const MOD: i64 = 1000000007; // const MOD: i64 = 998244353; const T: bool = true; const F: bool = false; 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; use crate::kraskal::kraskal; macro_rules! p { ($x:expr) => { println!("{}", $x); }; } macro_rules! d { ($x:expr) => { println!("{:?}", $x); }; } macro_rules! dd { (x:expr) => { dbg!(x); }; } macro_rules! chmin { ($base:expr, $($cmps:expr),+ $(,)*) => {{ let cmp_min = min!($($cmps),+); if $base > cmp_min { $base = cmp_min; true } else { false } }}; } macro_rules! chmax { ($base:expr, $($cmps:expr),+ $(,)*) => {{ let cmp_max = max!($($cmps),+); if $base < cmp_max { $base = cmp_max; true } else { false } }}; } macro_rules! min { ($a:expr $(,)*) => {{ $a }}; ($a:expr, $b:expr $(,)*) => {{ std::cmp::min($a, $b) }}; ($a:expr, $($rest:expr),+ $(,)*) => {{ std::cmp::min($a, min!($($rest),+)) }}; } macro_rules! max { ($a:expr $(,)*) => {{ $a }}; ($a:expr, $b:expr $(,)*) => {{ std::cmp::max($a, $b) }}; ($a:expr, $($rest:expr),+ $(,)*) => {{ std::cmp::max($a, max!($($rest),+)) }}; } // 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_vec2(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(), ) } #[allow(dead_code)] 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 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(), ) } 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(), ) } 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::>>() } } mod kraskal { use crate::Dsu; #[derive(Clone, Copy, Debug)] pub struct Edge { pub u: usize, pub v: usize, pub cost: i64, } #[doc = "es: undirected edges. O(ElogV)"] pub fn kraskal(n: usize, ess: Vec<(usize, usize, usize)>) -> (Vec, Vec) { let mut used = vec![]; let mut unused = vec![]; let mut x = 0 as usize; let mut es = vec![]; for i in 0..ess.len() { let mut e = Edge { u: ess[i].0, v: ess[i].1, cost: ess[i].2 as i64, }; es.push(e); } es.sort_by_key(|x| x.cost); let mut uf = Dsu::new(n); for e in es { if !uf.same(e.u, e.v) { uf.merge(e.u, e.v); used.push(e); } else { unused.push(e); } } (used, unused) } pub fn kraskal_es(n: usize, es: Vec) -> (Vec, Vec) { let mut used = vec![]; let mut unused = vec![]; let mut es = es; es.sort_by_key(|x| x.cost); let mut uf = Dsu::new(n); for e in es { if !uf.same(e.u, e.v) { uf.merge(e.u, e.v); used.push(e); } else { unused.push(e); } } (used, unused) } } fn solve() { let n: usize = read(); let mut vp = vec![]; for i in 0..n * (n - 1) / 2 { let mut p = readuuu(); p.0 -= 1; p.1 -= 1; vp.push(p); } let r = kraskal(n, vp); let mut res = 0; for i in 0..(r.0).len() { res = max(res, (r.0)[i].cost as usize); } println!("{:?}", res); return; } fn main() { solve(); }