module Enumerable
    def repeated_permutation(size, &blk)
        f = proc do |memo, &blk|
            if memo.size == size
                blk.call memo
            else
                self.each do |i|
                    f.call memo + [i], &blk
                end
            end
        end

        if block_given?
            f.call [], &blk
        else
            Enumerator.new(f, :call, [])
        end
    end
end

def calc(exps)
    if exps.size == 1
        Ops.repeated_permutation(exps.first.scan(OpMark).size) do |ordered_ops|
            expr = "#{exps.first}"
            ordered_ops.each do |op|
                expr.sub!(OpMark, op.to_s)
            end
            result = eval(expr.gsub(/[0-9]+/){|s| "Rational(#{s})" }) rescue "Error"
            puts "#{expr} = #{result}"
        end
    else
        for i in 0..exps.size - 2
            calc exps[0, i] + ["(#{exps[i]}#{OpMark}#{exps[i + 1]})"] + exps[(i + 2)..-1]
        end
    end
end

require "rational"
Ops = [:+, :-, :*, :/]
OpMark = "<op>"
nums = ARGV.map &:to_i
calc nums