// 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, usize1) => (read_value!($next, usize) - 1); ($next:expr, $t:ty) => ($next().parse::<$t>().expect("Parse error")); } 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(); } fn dfs(v: usize, par: usize, g: &[Vec]) -> (i64, i64) { let n = g.len(); let mut sz = 1; let mut tot = 0; for &w in &g[v] { if w == par { continue; } let (subsz, subtot) = dfs(w, v, g); tot += subsz * (n as i64 - subsz); sz += subsz; tot += subtot; } (sz, tot) } // Tags: sum-of-distances-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 (_sz, tot) = dfs(0, n, &g); println!("{}", 2 * tot + n as i64 * n as i64); }