#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i=0;i<n;i++)

int main(){
  string s;
  cin>>s;
  int n=s.length();
  vector<int>vec;
  rep(i,n) vec.push_back(s[i]-'0');
  sort(vec.begin(),vec.end(),greater<int>());
  rep(i,n){
    cout<<vec[i];
  }
  cout<<endl;
  return 0;
}