import java.io.File;
import java.io.FileNotFoundException;
import java.util.Arrays;
import java.util.Scanner;

public class EX05A_Number {
	public static void main(String[] args) throws FileNotFoundException {
		File file = new File("ex05.txt");
		Scanner fin = new Scanner(file);
		String num = fin.nextLine();
		int len = num.length();
		char[] cars = num.toCharArray();
		Arrays.sort(cars);
		for(int k=len-1; k >= 0 ; k--)  {
			System.out.printf("%c", cars[k]);
		}
	}
}