class Yukicoder
  def initialize
    n = gets.chomp
    size = n.size
    max_val = n.to_i

    0.upto(size-2) do |i|
      i.upto(size-1) do |j|
        num = n.dup
        num[i], num[j] = num[j], num[i]
        num = num.to_i

        if max_val < num
          max_val = num
        end
      end
    end

    puts max_val
  end
end

Yukicoder.new