package m.shin;
import java.util.Arrays;
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[n.length()];
		for(int i = 0;i < n.length();i++){
			a[i] = -1 * Integer.parseInt(n.substring(i, i+1));
		}
		Arrays.sort(a);
		for(int i = 0;i < n.length();i++){
			System.out.print(-1 * a[i]);
		}
		System.out.println();

	}

}