Create the Entity Relationship Diagram(ERD) for following hospital scenario. For Patient entity illustrates its attributes. Highlight key attribute in red.

Patients are treated in single ward by doctors assigned to them. Generally each patient will be assigned single doctor, but in rare cases they will have two. Healthcare Assistants also attend to patients, number of these are associated with each ward. Initially the system will be concerned completely with drug treatment. Each patient is needed to take variety of drugs certain number of times per day and for varying lengths of time.