# -*- coding: utf-8 -*-
"""
No.256 桁の数字を入れ替え (2)
https://yukicoder.me/problems/no/256

"""
import sys
from sys import stdin
input = stdin.readline


def main(args):
    N = list(input().strip())
    N.sort(reverse=True)
    print(''.join(N))


if __name__ == '__main__':
    main(sys.argv[1:])