Let's define a string \lt x \gt as an opening tag, where x is any small letter of the Latin alphabet. Each opening tag matches a closing tag of the type \lt /x \gt , 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'= \lt a \gt +s+ \lt /a \gt 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.
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.
\lt a \gt \lt b \gt \lt c \gt \lt /c \gt \lt /b \gt \lt /a \gt· · · ·· · · ·· · · ·· · · ·· · · ·· · · \n
\lt a \gt \lt b \gt \lt c \gt \lt /c \gt \lt /b \gt \lt /a \gt· · · ··· · · ··· · · ··· · · ··· · · \n · · · \n
\lt a \gt \lt b \gt \lt /b \gt \lt d \gt \lt c \gt \lt /c \gt \lt /d \gt \lt /a \gt· · · ·· · · ·· · · ·· · · ·· · · ·· · · ·· · · ·· · · \n
\lt a \gt \lt b \gt \lt /b \gt \lt d \gt \lt c \gt \lt /c \gt \lt /d \gt \lt /a \gt· · · ··· · · ··· · · ··· · · ··· · · ··· · · ··· · · \n · · · \n