import java.util.Arrays;
import java.util.Scanner;

public class Main{
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
while (scanner.hasNextLine()) {
String string = scanner.nextLine();
char[] chars = string.toCharArray();
Arrays.sort(chars);
String s = String.valueOf(chars);
System.out.println(s);
}
}
}