SELECT COUNT ( DISTINCT t2.name ) 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 t1.name  =  "H. V. Jagadish";
return me the number of authors who have cooperated with " H. V. Jagadish " .