#!/usr/bin/ruby

class Array
    def swap!(a, b)
        self[a], self[b] = self[b], self[a]
        self
    end
    def shuffle!
        each_index do |i|
            j = i + rand(length - i)
            swap!(i, j)
        end
        self
    end
end

ARGF.readlines.shuffle!.each { |line| puts line }