CF125B.Simple XML

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.

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.

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