List down the report number of crimes associated with the district commander named Jill M. Stevens.
report number refers report_no; 'Jill M. Stevens" is the commander
SELECT SUM(CASE WHEN T1.commander = 'Jill M. Stevens' THEN 1 ELSE 0 END) FROM District AS T1 INNER JOIN Crime AS T2 ON T1.district_no = T2.district_no