# frozen_string_literal: true

class String
  def digit_only
    sub!(/[a-zA-Z]/, '').nil?
  end
end

max = 12_345

a = gets.chomp
b = gets.chomp

leading_zero = a.size > 1 && a[0] == '0' || b.size > 1 && b[0] == '0'
both_digit_only = a.digit_only && b.digit_only
out_range = a.to_i > max || b.to_i > max

puts(leading_zero || !both_digit_only || out_range ? 'NG' : 'OK')