import java.util.Scanner;public class Main {    private static char[] ASCII = {        ‘a‘,‘b‘,‘c‘,‘d‘,‘e‘,‘f‘,‘g‘,‘h‘,‘i‘,‘j‘,‘k‘,‘l‘,‘m‘,‘n‘,‘o‘,‘p‘,‘q‘,‘r‘,‘s‘,‘t‘,‘u‘,‘v‘,‘w‘,‘x‘,‘y‘,‘z‘    };    private static String getString() {        Scanner input = new Scanner(System.in);        return input.nextLine();    }        private static boolean isLetter(char c) {        if ((‘a‘ <= c) && (c <= ‘z‘)) {            return true;        }        return false;    }        private static int[] getSortArray(String str, int[] letters) {        for (int i = 0; i < str.length(); i++) {            if (isLetter(str.charAt(i))) {                letters[str.charAt(i) - ‘a‘]++;            }        }                return letters;    }        public static void main(String[] args) {        String str = getString();                int[] letters = new int[26];        letters = getSortArray(str, letters);                for (int i = 0; i < letters.length; i++) {            for (int j = 0; j < letters[i]; j++) {                System.out.print(ASCII[i] + "");            }        }        System.out.print("\n");    }}