Database: academic
Question: return me the number of papers written by " H. V. Jagadish " and " Divesh Srivastava " before 2000 .
SQL: select count ( distinct t5.title ) from writes as t3 join author as t2 on t3.aid  =  t2.aid join publication as t5 on t3.pid  =  t5.pid join writes as t4 on t4.pid  =  t5.pid join author as t1 on t4.aid  =  t1.aid where t2.name  =  "h. v. jagadish" and t1.name  =  "divesh srivastava" and t5.year  <  2000;