#include <bits/stdc++.h>
using namespace std;
int main(){
string s;
cin>>s;
int a[10] = {};
for(int i=0;i<s.length();++i) {
  a[s[i] - '0'] ++;
}
for (int i=9;i>=0;--i) {
  for (int j = 0; j < a[i]; ++j) {
    cout << i;
  }
 }
cout << endl;
}