#include <algorithm>
#include <cmath>
#include <cstdio>
#include <deque>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>

using namespace std;

typedef long long ll;

#define MOD 1000000007

int main() {
  string s;
  cin >> s;
  int n = s.size();
  vector<int> cnt(10);
  for (int i = 0; i < n; ++i) {
    cnt[s[i] - '0']++;
  }
  for (int i = 9; i >= 0; --i) {
    for (int j = 0; j < cnt[i]; ++j) {
      cout << i;
    }
  }
  cout << endl;
  return 0;
}