import java.util.*;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    String N = sc.next();
    int len = N.length();
    int[] num = new int[len];
    for(int i = 0; i < len; i++) {
      num[i] = Integer.parseInt(String.valueOf(N.charAt(i)));
    }
    Arrays.sort(num);
    String ans = "";
    for(int i = len - 1; i >= 0; i--) {
      ans += String.valueOf(num[i]);
    }
    System.out.println(ans);
  }
}