Which cities have the top 5 lowest enrollment number for students in grades 1 through 12?
K-12 refers to students in grades 1 through 12.
SELECT T2.City FROM frpm AS T1 INNER JOIN schools AS T2 ON T1.CDSCode = T2.CDSCode GROUP BY T2.City ORDER BY SUM(T1.`Enrollment (K-12)`) ASC LIMIT 5