Database: academic_minus_1_1
Question: return me the number of papers written by " H. V. Jagadish " and " Divesh Srivastava " before 2000 .
SQL: select count ( distinct t2.title ) from writes_author as t1 join publication as t2 on t1.pid = t2.pid where t1.name = 'h. v. jagadish' and t1.name = 'divesh srivastava' and t2.year < 2000 ;