import java.io.*;
import java.util.*;
public class Main{
public static void main(String[] args) throws Exception{
Scanner sc = new Scanner(System.in);
while(sc.hasNextLine()){
String line = sc.nextLine();
char[] cc = line.toCharArray();
Arrays.sort(cc);
for(char c : cc){
System.out.print(c);
}
System.out.println();
}
}
} 


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