FOR i IN 1..4 LOOP
SELECT COUNT(*)
INTO v_student
FROM student_detail
WHERE grade IN (CASE WHEN i = 1 THEN 'F1'
                    WHEN i = 2 THEN 'F2'  
                    WHEN i = 3 THEN 'F3' 
                    WHEN i = 4 THEN 'F4','F5'
                END);
dbms_output.put_line(Loop: '||i);
dbms_output.put_line('No of students is: '||v_student);
END LOOP;

  IF i = 4 THEN
    SELECT COUNT(*)
    FROM student_detail
    WHERE grade IN ('F4','F5'); 
  END IF; 
 

FOR i IN 1..4 LOOP
SELECT COUNT(*)
INTO v_student
FROM student_detail
WHERE grade IN (CASE WHEN i = 1 THEN 'F1'
                    WHEN i = 2 THEN 'F2'  
                    WHEN i = 3 THEN 'F3' 
                    WHEN i = 4 THEN '''F4'',''F5'''
                END);
dbms_output.put_line(Loop: '||i);
dbms_output.put_line('No of students is: '||v_student);
END LOOP;