package main

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

func main() {
	N := nextLine()

	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 s = bufio.NewScanner(os.Stdin)

func next() string {
	s.Split(bufio.ScanWords)
	s.Scan()
	return s.Text()
}
func nextLine() string {
	s.Split(bufio.ScanLines)
	s.Scan()
	return s.Text()
}

func nextInt() int {
	i, e := strconv.Atoi(next())
	if e != nil {
		panic(e)
	}
	return i
}
func nextLong() int64 {
	i, e := strconv.ParseInt(next(), 10, 64)
	if e != nil {
		panic(e)
	}
	return i
}

func max(a int, b int) int {
	if a < b {
		return b
	}
	return a
}