/* -*- coding: utf-8 -*-
 *
 * 256.cc: No.256 桁の数字を入れ替え (2) - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 100000;

/* typedef */

/* global variables */

char cs[MAX_N + 1];

/* subroutines */

/* main */

int main() {
  scanf("%s", cs);

  int n = strlen(cs);
  sort(cs, cs + n, greater<char>());

  for (int i = 0; i < n; i++) putchar(cs[i]);
  putchar('\n');
  return 0;
}