GATE Computer Science (CS) 2022 Shift 1 Solved Paper

Consider the relational database with the following four schemas and their respective instances.
Student(sNo, sName, dNo) Dept(dNo, dName)
Course(cNo, cName, dNo) Register(sNo, cNo)
     
SQL Query:
SELECT * FROM Student AS S WHERE NOT EXIST
(SELECT cNo FROM Course WHERE dNo = “D01”
EXCEPT
SELECT cNo FROM Register WHERE sNo = S.sNo)
The number of rows returned by the above SQL query is___________.