Codeforces#294 Div2-B

gistfile1.rb

# http://codeforces.com/contest/519/problem/B
class Errors
  def initialize(a, b, c)
    @errors = [a, b, c].map(&:sort)
  end

  def corrected_error(n)
    (0..@errors[n - 1].length).each do |idx|
      return @errors[n - 1][idx] if @errors[n][idx] != @errors[n - 1][idx]
    end
  end
end

n = gets.chomp.to_i
a = gets.chomp.split.map(&:to_i)
b = gets.chomp.split.map(&:to_i)
c = gets.chomp.split.map(&:to_i)

erros = Errors.new(a, b, c)
puts erros.corrected_error(1)
puts erros.corrected_error(2)