package backjoon;

// https://www.acmicpc.net/problem/1427

// 소트인사이드

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.util.Arrays;

import java.util.Collections;

public class _1427 {

public static void main(String[] args) throws IOException {

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

//sol memory 11712 runtime 80

String[] N = br.readLine().split("");

Integer[] arr = new Integer[N.length];

for(int i =0; i<N.length; i++){

arr[i] = Integer.parseInt(N[i]);

}

Arrays.sort(arr, Collections.reverseOrder());

StringBuilder sb = new StringBuilder();

for(int i : arr){

sb.append(i);

}

System.out.println(sb);

}

}

/*

input

2143

output

4321

*/