#include <iostream>
#include <cmath>
#include <algorithm>
using namespace std;

int main(){
   int d,n; cin >> n;
   int digit[6] = {};
   d = log10(n) + 1;
   for(int i = 0;i < d;i++){
      digit[i] = n % 10;
      n /= 10;
   }
   stable_sort(digit,digit + 6);
   for(int i = 5;i >= 6 - d;i--){
      cout << digit[i];
   }
   cout << endl;
}