import java.util.Arrays;
import java.util.Scanner;

public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		while(sc.hasNext()){
			char[] c=(sc.next()).toCharArray();
			Arrays.sort(c);
			for(int i=c.length-1;i>=0;i--) System.out.print(c[i]);
			System.out.println();
		}
	}
}