package m.shin;
import java.util.Scanner;
public class Con256 {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		String n = s.nextLine();
		s.close();

		int[] a = new int[10];
		for(int i = 0;i < n.length();i++){
			a[Integer.parseInt(n.substring(i, i+1))]++;
		}
		n = "";
		for(int i = 9;i >= 0;i--){
			for(int j = 0;j < a[i];j++){
				n += Integer.toString(i);
			}
		}
		System.out.println(n);

	}

}