void solve(string s)
{
 vector<int>num;
 for(auto i : s)
  num.push_back(i - '0');
 sort(num.begin(), num.end(), greater<>());

 string front = "", back = "";
 for(int i = 0; i < num.size(); i++)
  if (i%2 == 0)
   front += (char)('0'+num[i]);
  else
   back += (char)('0'+num[i]);

 reverse(back.begin(), back.end());
 front += back;
 cout << front;

}