#[allow(unused_macros)] macro_rules! input { (source = $s:expr, $($r:tt)*) => { let mut iter = $s.split_whitespace(); input_inner!{iter, $($r)*} }; ($($r:tt)*) => { let s = { use std::io::Read; let mut s = String::new(); std::io::stdin().read_to_string(&mut s).unwrap(); s }; let mut iter = s.split_whitespace(); input_inner!{iter, $($r)*} }; } #[allow(unused_macros)] macro_rules! input_inner { ($iter:expr) => {}; ($iter:expr, ) => {}; ($iter:expr, $var:ident : $t:tt $($r:tt)*) => { let $var = read_value!($iter, $t); input_inner!{$iter $($r)*} }; } #[allow(unused_macros)] macro_rules! read_value { ($iter:expr, ( $($t:tt),* )) => { ( $(read_value!($iter, $t)),* ) }; ($iter:expr, [ $t:tt ; $len:expr ]) => { (0..$len).map(|_| read_value!($iter, $t)).collect::>() }; ($iter:expr, chars) => { read_value!($iter, String).chars().collect::>() }; ($iter:expr, usize1) => { read_value!($iter, usize) - 1 }; ($iter:expr, $t:ty) => { $iter.next().unwrap().parse::<$t>().expect("Parse error") }; } fn dfs(s: usize, graph:&Vec>, used: &mut Vec, d: &mut Vec, cd: i32) { used[s] = true; d[s] = cd; for g in &graph[s] { if !used[*g] { dfs(*g, graph, used, d, cd+1); } } } fn main() { input! { n: usize, edges: [(usize1, usize1); (n-1)], } let mut deg: Vec = vec![0; n]; for (s, v) in &edges { deg[*s] += 1; deg[*v] += 1; } let mut ans = 0; for i in ° { ans += std::cmp::max(i-2, 0); } println!("{}", ans); // println!("{:?}", d); }