import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner cin=new Scanner(System.in);
		String a;
		char[] b;
		while(cin.hasNext()){
			a=cin.nextLine();
			b=a.toCharArray();
			Arrays.sort(b);
			a="";
			for(int i=0;i<b.length;i++)
				a+=b[i];
			System.out.println(a);
		}
	}

}

/**************************************************************
	Problem: 2201
	User: admin
	Language: Java
	Result: Accepted
	Time:1038 ms
	Memory:44032 kb
****************************************************************/