import java.util.*;

public class Test{
    public static void main(String[] args){
        Scanner s = new Scanner(System.in);
        String str = s.next();

        int[] num = new int[str.length()];

        for(int i=0;i<str.length();i++){
        	num[i] = Integer.parseInt(String.valueOf(str.charAt(i)));
        }

        Arrays.sort(num);

        for(int i=num.length-1;i>=0;i--){
        	System.out.print(num[i]);
        	if(i==0)
        		System.out.println();
        }
    }
}