Find the number of patients who are not using the medication of Procrastin-X.
SELECT count(*) FROM patient WHERE SSN NOT IN ( SELECT T1.patient FROM Prescribes AS T1 JOIN Medication AS T2 ON T1.Medication  =  T2.Code WHERE T2.name  =  'Procrastin-X' )
Procrastin-X ilacını kullanmayan hasta sayısını bulun.