baekjoon 1427

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb = new StringBuilder();
        String[] N = br.readLine().split("");
        String tmp = null;
        for (int j = 0; j < N.length - 1; j++){
            for (int i = 0; i < N.length - 1; i++){
                if (Integer.parseInt(N[i]) < Integer.parseInt(N[i+1])){
                    tmp = N[i];
                    N[i] = N[i+1];
                    N[i+1] = tmp;
                }
            }
        }
        for (int i = 0; i < N.length; i++)
            sb.append(N[i]);
        System.out.print(sb);
        br.close();
    }
}