#![allow(unused_imports)] #![allow(non_snake_case)] use std::cmp::*; use std::collections::*; use std::io::Write; #[allow(unused_macros)] macro_rules! debug { ($($e:expr),*) => { #[cfg(debug_assertions)] $({ let (e, mut err) = (stringify!($e), std::io::stderr()); writeln!(err, "{} = {:?}", e, $e).unwrap() })* }; } fn main() { let n = read::(); let mut uft = UnionFindTree::new(n); let mut count = vec![0; n]; for i in 0..n - 1 { let v = read_vec::(); let (u, v) = (v[0], v[1]); uft.unite(u, v); count[u] += 1; count[v] += 1; } let elem = (0..n).map(|x| uft.find(x)).collect::>().len(); let count_one = count.into_iter().any(|num| num == 1); if elem > 2 || (elem == 2 && count_one) { println!("Alice"); } else { println!("Bob"); } } fn read() -> T { let mut s = String::new(); std::io::stdin().read_line(&mut s).ok(); s.trim().parse().ok().unwrap() } fn read_vec() -> Vec { read::() .split_whitespace() .map(|e| e.parse().ok().unwrap()) .collect() } #[derive(Debug, Clone)] struct UnionFindTree { parent: Vec, size: Vec, height: Vec, } impl UnionFindTree { fn new(n: usize) -> UnionFindTree { UnionFindTree { parent: vec![-1; n], size: vec![1usize; n], height: vec![0u64; n], } } fn find(&mut self, index: usize) -> usize { if self.parent[index] == -1 { return index; } let idx = self.parent[index] as usize; let ret = self.find(idx); self.parent[index] = ret as isize; ret } fn same(&mut self, x: usize, y: usize) -> bool { self.find(x) == self.find(y) } fn get_size(&mut self, x: usize) -> usize { let idx = self.find(x); self.size[idx] } fn unite(&mut self, index0: usize, index1: usize) -> bool { let a = self.find(index0); let b = self.find(index1); if a == b { false } else { if self.height[a] > self.height[b] { self.parent[b] = a as isize; self.size[a] += self.size[b]; } else if self.height[a] < self.height[b] { self.parent[a] = b as isize; self.size[b] += self.size[a]; } else { self.parent[b] = a as isize; self.size[a] += self.size[b]; self.height[a] += 1; } true } } }