return me the number of conferences which have papers by " H. V. Jagadish " .
SELECT COUNT ( DISTINCT t2.name ) FROM publication AS t4 JOIN conference AS t2 ON t4.cid  =  t2.cid JOIN writes AS t3 ON t3.pid  =  t4.pid JOIN author AS t1 ON t3.aid  =  t1.aid WHERE t1.name  =  "H. V. Jagadish";
SELECT COUNT ( DISTINCT t2.name ) FROM publication AS t4 JOIN conference AS t2 ON t4.cid  =  t2.cid JOIN writes AS t3 ON t3.pid  =  t4.pid JOIN author AS t1 ON t3.aid  =  t1.aid WHERE t1.name  =  "H. V. Jagadish";
[{'COUNT ( DISTINCT t2.name )': 0}]