#![allow(unused_imports)] #![allow(non_snake_case, unused)] use std::cmp::*; use std::collections::*; use std::ops::*; macro_rules! eprint { ($($t:tt)*) => {{ use ::std::io::Write; let _ = write!(::std::io::stderr(), $($t)*); }}; } macro_rules! eprintln { () => { eprintln!(""); }; ($($t:tt)*) => {{ use ::std::io::Write; let _ = writeln!(::std::io::stderr(), $($t)*); }}; } macro_rules! dbg { ($v:expr) => {{ let val = $v; eprintln!("[{}:{}] {} = {:?}", file!(), line!(), stringify!($v), val); val }} } macro_rules! mat { ($($e:expr),*) => { Vec::from(vec![$($e),*]) }; ($($e:expr,)*) => { Vec::from(vec![$($e),*]) }; ($e:expr; $d:expr) => { Vec::from(vec![$e; $d]) }; ($e:expr; $d:expr $(; $ds:expr)+) => { Vec::from(vec![mat![$e $(; $ds)*]; $d]) }; } macro_rules! ok { ($a:ident$([$i:expr])*.$f:ident()$(@$t:ident)*) => { $a$([$i])*.$f($($t),*) }; ($a:ident$([$i:expr])*.$f:ident($e:expr$(,$es:expr)*)$(@$t:ident)*) => { { let t = $e; ok!($a$([$i])*.$f($($es),*)$(@$t)*@t) } }; } pub fn readln() -> String { let mut line = String::new(); ::std::io::stdin().read_line(&mut line).unwrap_or_else(|e| panic!("{}", e)); line } macro_rules! read { ($($t:tt),*; $n:expr) => {{ let stdin = ::std::io::stdin(); let ret = ::std::io::BufRead::lines(stdin.lock()).take($n).map(|line| { let line = line.unwrap(); let mut it = line.split_whitespace(); _read!(it; $($t),*) }).collect::>(); ret }}; ($($t:tt),*) => {{ let line = readln(); let mut it = line.split_whitespace(); _read!(it; $($t),*) }}; } macro_rules! _read { ($it:ident; [char]) => { _read!($it; String).chars().collect::>() }; ($it:ident; [u8]) => { Vec::from(_read!($it; String).into_bytes()) }; ($it:ident; usize1) => { $it.next().unwrap_or_else(|| panic!("input mismatch")).parse::().unwrap_or_else(|e| panic!("{}", e)) - 1 }; ($it:ident; [usize1]) => { $it.map(|s| s.parse::().unwrap_or_else(|e| panic!("{}", e)) - 1).collect::>() }; ($it:ident; [$t:ty]) => { $it.map(|s| s.parse::<$t>().unwrap_or_else(|e| panic!("{}", e))).collect::>() }; ($it:ident; $t:ty) => { $it.next().unwrap_or_else(|| panic!("input mismatch")).parse::<$t>().unwrap_or_else(|e| panic!("{}", e)) }; ($it:ident; $($t:tt),+) => { ($(_read!($it; $t)),*) }; } pub fn main() { let _ = ::std::thread::Builder::new().name("run".to_string()).stack_size(32 * 1024 * 1024).spawn(run).unwrap().join(); } const MOD: usize = 1_000_000_007; const INF: usize = std::usize::MAX/2; pub trait SetMinMax { fn setmin(&mut self, v: Self) -> bool; fn setmax(&mut self, v: Self) -> bool; } impl SetMinMax for T where T: PartialOrd { fn setmin(&mut self, v: T) -> bool { *self > v && { *self = v; true } } fn setmax(&mut self, v: T) -> bool { *self < v && { *self = v; true } } } pub struct UnionFind { data: Vec, } impl UnionFind { /// Creates a object with n disjoint sets. `i`-th set is `{ i }`. pub fn new(n: usize) -> UnionFind { UnionFind { data: vec![-1; n] } } /// Unite a set including `x` and another set including y into one. /// Returns `true` only if they were in different set. pub fn unite(&mut self, x: usize, y: usize) -> bool { let x = self.root(x); let y = self.root(y); if x != y { let (x, y) = if self.data[x] <= self.data[y] { (x, y) } else { (y, x) }; self.data[x] += self.data[y]; self.data[y] = x as i32; } x != y } /// Returns `true` only if `x` and `y` are in a same set. pub fn same(&mut self, x: usize, y: usize) -> bool { self.root(x) == self.root(y) } /// Returns the number of elements of a set including `x`. pub fn size(&mut self, x: usize) -> u32 { let r = self.root(x); (-self.data[r]) as u32 } /// internal method to return representative element of a set including `x`. pub fn root(&mut self, x: usize) -> usize { if self.data[x] < 0 { x } else { let nx = self.data[x] as usize; let r = self.root(nx); self.data[x] = r as i32; r } } } fn solve() { let n = read!(usize); let e = read!([usize];n-1); let mut v = vec![0;n]; let mut uf = UnionFind::new(n); for i in e { v[i[0]] += 1; v[i[1]] += 1; uf.unite(i[0],i[1]); } let mut s = (0..n).map(|x| uf.root(x)).collect::>(); let size = s.len(); if size==1 { println!("Bob"); } else if size==2 { if let Some(k) = v.iter().position(|x| *x>2){ println!("Alice"); } else { println!("Bob"); } } else { println!("Alice"); } } fn run() { solve(); }