Among professors with the highest teachability, how many of their students have high salary?
highest teachability refers to MAX(teachability); high salary refers to salary = 'high';
SELECT COUNT(T1.student_id) FROM RA AS T1 INNER JOIN prof AS T2 ON T1.prof_id = T2.prof_id WHERE T1.salary = 'high' ORDER BY T2.teachingability DESC LIMIT 1
database name:db_id cs_semester
course table course Cols: course id dtype integer, name dtype text, credit dtype integer, difficulty dtype integer, 
prof table prof Cols: professor id dtype integer, gender dtype text, first name dtype text, last name dtype text, email dtype text, popularity dtype integer, teaching ability dtype integer, graduate from dtype text, 
RA table RA Cols: student id dtype integer, capability dtype integer, professor id dtype integer, salary dtype text, 
registration table registration Cols: course id dtype integer, student id dtype integer, grade dtype text, satisfying degree dtype integer, 
student table student Cols: student id dtype integer, first name dtype text, last name dtype text, phone number dtype text, email dtype text, intelligence dtype integer, graduate point average dtype real, type dtype text, 
