#[allow(unused_imports)] use std::cmp::*; #[allow(unused_imports)] use std::collections::*; use std::io::{Write, BufWriter}; // https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8 macro_rules! input { ($($r:tt)*) => { let stdin = std::io::stdin(); let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock())); let mut next = move || -> String{ bytes.by_ref().map(|r|r.unwrap() as char) .skip_while(|c|c.is_whitespace()) .take_while(|c|!c.is_whitespace()) .collect() }; input_inner!{next, $($r)*} }; } macro_rules! input_inner { ($next:expr) => {}; ($next:expr,) => {}; ($next:expr, $var:ident : $t:tt $($r:tt)*) => { let $var = read_value!($next, $t); input_inner!{$next $($r)*} }; } macro_rules! read_value { ($next:expr, ( $($t:tt),* )) => { ($(read_value!($next, $t)),*) }; ($next:expr, [ $t:tt ; $len:expr ]) => { (0..$len).map(|_| read_value!($next, $t)).collect::>() }; ($next:expr, chars) => { read_value!($next, String).chars().collect::>() }; ($next:expr, usize1) => (read_value!($next, usize) - 1); ($next:expr, [ $t:tt ]) => {{ let len = read_value!($next, usize); read_value!($next, [$t; len]) }}; ($next:expr, $t:ty) => ($next().parse::<$t>().expect("Parse error")); } trait Change { fn chmax(&mut self, x: Self); fn chmin(&mut self, x: Self); } impl Change for T { fn chmax(&mut self, x: T) { if *self < x { *self = x; } } fn chmin(&mut self, x: T) { if *self > x { *self = x; } } } fn main() { // In order to avoid potential stack overflow, spawn a new thread. let stack_size = 104_857_600; // 100 MB let thd = std::thread::Builder::new().stack_size(stack_size); thd.spawn(|| solve()).unwrap().join().unwrap(); } const INF: i64 = 1 << 50; fn dfs(v: usize, par: usize, g: &[Vec], dp: &mut [[i64; 2]]) { let mut me = [-INF; 2]; let mut s = 0; let mut mi = INF; for &w in &g[v] { if w == par { continue; } dfs(w, v, g, dp); let poss = max(dp[w][0], dp[w][1]); s += poss; mi = min(mi, poss - dp[w][0]); } me[0] = s; me[1] = s - mi + 1; dp[v] = me; } // Tags: max-matching-on-trees fn solve() { input! { n: usize, ab: [(usize1, usize1); n - 1], } let mut g = vec![vec![]; n]; for &(a, b) in &ab { g[a].push(b); g[b].push(a); } let mut dp = vec![[-INF; 2]; n]; dfs(0, n, &g, &mut dp); println!("{}", max(dp[0][0], dp[0][1])); }