class Node attr_accessor :parent, :rank def initialize @parent = -1 # Positive value means its parent,and Negative value means its size. @rank = 0 end end class UnionFindTree def initialize(n) @nodes = (0...n).to_a.map { |i| Node.new } end def find(x) return @nodes[x].parent < 0 ? x : @nodes[x].parent = find(@nodes[x].parent) end def unite(a, b) a = find(a) b = find(b) return if a == b if @nodes[a].rank < @nodes[b].rank @nodes[b].parent += @nodes[a].parent @nodes[a].parent = b else @nodes[a].parent += @nodes[b].parent @nodes[b].parent = a @nodes[a].rank += 1 if @nodes[a].rank == @nodes[b].rank end end def same?(a, b) find(a) == find(b) end def size(a) -@nodes[find(a)].parent end # 確認用。アルゴリズムとは関係無い def parents @nodes.map(&:parent) end end # N, M = gets.split.map(&:to_i) class Bridge attr_accessor :first, :second def initialize @first = nil @second = nil end def nodes=(a) a[0], a[1] = a[1], a[0] if a[0] > a[1] @first = a[0] @second = a[1] end end n = gets.to_i # n, q = gets.split.map(&:to_i) g = Array.new(n){[]} uft = UnionFindTree.new(n) (n-1).times do |i| x,y = gets.split.map(&:to_i) # if com == 0 uft.unite(x, y) g[x] << y g[y] << x # else # puts uft.same?(x, y) ? 1 : 0 # end end z = g.map{|k| k.size} if uft.size(0) == n or uft.size(1) == n puts "Bob" elsif z.count(0) == 1 and z.count(2) == n-1 puts "Bob" else puts "Alice" end