Let's define a string as an opening tag, where x is any small letter of the Latin alphabet. Each opening tag matches a closing tag of the type , where x is the same letter. Tegs can be nested into each other: in this case one opening and closing tag pair is located inside another pair. Let's define the notion of a XML-text: an empty string is a XML-text if s is a XML-text, then s' =+ s + also is a XML-text, where a is any small Latin letter if s 1 , s 2 are XML-texts, then s 1 + s 2 also is a XML-text You are given a XML-text (it is guaranteed that the text is valid), your task is to print in the following form: each tag (opening and closing) is located on a single line print before the tag 2 * h spaces, where h is the level of the tag's nestedness.

输入描述:

The input data consists on the only non-empty string — the XML-text, its length does not exceed 1000 characters. It is guaranteed that the text is valid. The text contains no spaces.

输出描述:

Print the given XML-text according to the above-given rules.