Unique Sorted String

Given a string consisting of only lowercase letters, your task is to produce a new string that contains each distinct letter exactly once, and in sorted (alphabetical) order. More formally, if the input string is \( s \) then you should output the string \( t \) such that:

• Each letter in \( t \) appears in \( s \) at least once.
• Each letter appears only once in \( t \).
• The letters in \( t \) are sorted in increasing order (i.e. from 'a' to 'z').

Print the resulting string to stdout.

inputFormat

The input consists of a single line containing a string \( s \) made up of lowercase letters. Note that \( s \) might be empty.

outputFormat

Output a single string that contains the unique characters from \( s \) in sorted order.

banana

abn