import java.util.*;

public class Exercise62{
  public static void main (String[] args){

    Scanner sc = new Scanner(System.in);

    String str = sc.next();

    String[] array = str.split("");

    int[] nums = new int[array.length];

    for (int i = 0; i < array.length; i++){
      nums[i] = Integer.parseInt(array[i]);
    }

    Arrays.sort(nums);

    int sum = 0;
    int digit = 1;

    for (int i = 0; i < nums.length; i++){
      sum += nums[i] * digit;
      digit *= 10;
    }

    System.out.println(sum);
  }
}