import java.util.*;

public class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		String[] s = sc.next().split("");
		int[] ar = new int[s.length];
		for (int i=0; i<s.length; i++) {
			ar[i] = Integer.parseInt(s[i]);
		}
		Arrays.sort(ar);
		for (int i=ar.length-1; i>=0; i--) {
			System.out.print(ar[i]);
		}
	}
}