package main

import (
	"fmt"
	"bufio"
	"os"
	"strconv"
	"sort"
)

func main() {
	N := readLine()

	d := make([]int, len(N))
	for i := 0; i < len(N); i++ {
		d[i] = int(N[i] - uint8('0'))
	}
	sort.Ints(d)

	ans := ""
	k := len(N)
	for i := 0; i < k; i++ {
		ans+=strconv.Itoa(d[k-i-1])
	}

	fmt.Println(ans)
}

var rdr = bufio.NewReaderSize(os.Stdin, 1000000)

func readLine() string {
	buf := make([]byte, 0, 1000000)
	for {
		l, p, e := rdr.ReadLine()
		if e != nil {
			panic(e)
		}
		buf = append(buf, l...)
		if !p {
			break
		}
	}
	return string(buf)
}