#! /usr/local/bin/ruby

class Tarai
  def initialize
    @cache = Hash.new do |hash, key|
      hash[key] = Hash.new do |hash, key|
        hash[key] = {}
      end
    end
  end
  
  def call(x, y, z)
    return y if x <= y
    @cache[x][y][z] ||= call(
      call(x - 1, y, z),
      call(y - 1, z, x),
      call(z - 1, x, y)
    )
  end
end

tarai = Tarai.new

p tarai.call(100, 50, 0)