#!/usr/bin/ruby

$a = []

def move( n )
  if n == 0
    print "0.#{$a.reverse.to_s}\n"
    return
  end

  # move to the left
  $a[n] = 0
  move( n - 1 )

  # move to the right
  $a[n] = 1
  move( n - 1 )
end

move( 4 )