#include<iostream>
using namespace std;
int main()
{
   string line, word;
   getline(cin, line);
   if (line.find('_')!=string::npos)
   {
       cout<<"Invalid input";
       return 0;
   }
   stringstream ss(line);
   vector<pair<int,string>> v;
   while(ss >> word)
   {
       for (char c : word)
       if (isdigit(c))
       v.push_back({c - '0', word});
   }
   sort(v.bgin(),v.end());
   for (auto &p : v)
   {
       for (char c : p.second)
       if(!isdigit(c))
       cout<<c;
       cout<<"";
   }
   return 0;
}