where to perform request parameters data type conversion: Controller or Model?

In a MVC application, where to perform request parameters data type conversion: Controller or Model?

For example I have 3 parameters coming with request: user_name, password, role_id. So I receive all 3 of them as string in the Controller. This is for example the Controller code:

public class MyServlet extends HttpServlet {
   protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      String userName = request.getParameter("user_name");
      String password = request.getParameter("password");
      String roleId = request.getParameter("role_id");
   }
}

The 3rd parameter has to be treated as an integer. So I have 2 choices:

1. convert it into an integer first in the Controller and then pass it to the Model.

In this case this is the Controller code:

public class MyServlet extends HttpServlet {
   protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      String userName = request.getParameter("user_name");
      String password = request.getParameter("password");
      String roleId = request.getParameter("role_id");
      int roleIdN = Integer.parseInt(roleId);
      MyService myService = new MyService();
      boolean result = myService.login(userName, password, roleIdN);
      ...
   }
}

And this is the Model code:

public class MyService {
   public boolean login(String userName, String password, int roleId) {
      ...
   }
}

2. pass it to the Model as String; the Model will convert it into an integer before using it.

In this case this is the Controller code:

public class MyServlet extends HttpServlet {
   protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      String userName = request.getParameter("user_name");
      String password = request.getParameter("password");
      String roleId = request.getParameter("role_id");
      MyService myService = new MyService();
      boolean result = myService.login(userName, password, roleId);
      ...
   }
}

And this is the Model code:

public class MyService {
   public boolean login(String userName, String password, String roleId) {
      int roleIdN = Integer.parseInt(roleId);
      ...
   }
}

Where it makes the most sense? I am trying to figure out the boundaries of both Controller and Model. What if the 3rd parameter does not contain a number?