1092:Simple XML

Time/Memory Limit:1000 MS/32768 K
Submitted: 53 Accepted: 18

 Problem Description

Let's define a string <x> as an opening tag, where x is any small letter of the Latin alphabet. Each opening tag matches a closing tag of the type </x>, 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'=<a>+s+</a> also is a XML-text, where a is any small Latin letter if s1, s2 are XML-texts, then s1+s2 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.

 Input

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.

 Output

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

 Sample Input

<a><b><c></c></b></a>

 Sample Output

<a>
  <b>
    <c>
    </c>
  </b>
</a> 

 Author

fzj

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