Remove Duplicates and Sort

Given a string ( S ), your task is to remove all duplicate characters so that each character appears only once, and then output the resulting string in lexicographical (alphabetical) order.

For example, for ( S = "bcabc" ), the unique characters are ( {a, b, c} ), and sorted order produces ( "abc" ).

inputFormat

The input consists of a single line containing the string ( S ). The string ( S ) may contain alphabets or other printable characters.

outputFormat

Output the string containing unique characters in lexicographical order.## sample

bcabc

abc