title: how to add a dot before each letter in a string in python
body: <p>we get a string from user and want to lowercase it and remove vowels and add a '.' before each letter of it. for example we get 'aBAcAba' and change it to '.b.c.b' . two early things are done but i want some help with third one.</p>
  <pre><code>str = input()
  str=str.lower()
  for i in range(0,len(str)):
      str=str.replace('a','')
      str=str.replace('e','')
      str=str.replace('o','')
      str=str.replace('i','')
      str=str.replace('u','')
  print(str)
  for j in range(0,len(str)):
      str=str.replace(str[j],('.'+str[j]))
  print(str)
  </code></pre>