import java.io.*;
import java.util.*;

public class Main{
    public static void main(String[] args) throws Exception{
        Scanner sc = new Scanner(System.in);
        while(sc.hasNextLine()){
            String line = sc.nextLine();
            char[] cc = line.toCharArray();
            Arrays.sort(cc);
            for(char c : cc){
                System.out.print(c);
            }
            System.out.println();
        }
    }
}