How many are there in mongo

  mongodb, question
> db.zhipin_cookie.find()[0]
 {
 "_id" : ObjectId("5c3e89b5cfab5493e7c04e1c"),
 "cookie" : [
 "_umdata=C234BF9D3AFA6FE77F94838529E088A9BBD97FE15A9C993647E1BA8899EBCF18025B4DFBCA9E6B73CD43AD3E795C914C12AFE595899E431C947FA6E1ED7DEB3B;   _uab_collina=154056544968891366026752;   JSESSIONID=\"\";   __c=1544930213;   __g=-;   __l=l=%2Fwww.zhipin.com%2Fjob_detail%2F0fa6383a3ce0cd951XR92dm_E1Q~.html&  r=https%3A%2F%2Fwww.baidu.com%2Flink%3Furl%3DmViDrfNXobBzHXLDRAMNB7UvOwByvB88ZEiALvXHu01RdCvB1_SFi8P9S6rfx7H4kc2WoT2-WLQ0-x-A4HFchKcom5EK8ofnYQ7Snen7sb  G%26wd%3D%26eqid%3D8b4d317e00010687000000035c15c3a1;   lastCity=101030100;   Hm_lvt_194df3105ad7148dcf2b98a91b5e727a=1547429880,1547429955,1547444163,1547515045;   toUrl=https%3A%2F%2Fwww.zhipin.com%2Fgongsi%2F;   Hm_lpvt_194df3105ad7148dcf2b98a91b5e727a=1547601953;  __a=85347837.1534956138.1539538585.1544930213.643.4.587.643",
 "__a=75861541.1547056683.1547056683.1547056687.438.2.437.438;   Hm_lvt_194df3105ad7148dcf2b98a91b5e727a=1547056684,1547056752,1547195723;   t=9PbhtSZ64hnq0qnh;   wt=9PbhtSZ64hnq0qnh;   sid=sem_pz_bdpc_dasou_title;   __g=sem_pz_bdpc_dasou_title;   __c=1547056687;   lastCity=101210100;   __l=r=https%3A%2F%2Fwww.zhipin.com%2F%3Fsid%3Dsem_pz_bdpc_dasou_title&l=%2Flogin.zhipin.com%2F%3Fka%3Dheader-login&g=%2Fwww.zhipin.com%2F%3Fsid%3Dsem_pz_bdpc_dasou_title;  Hm_lpvt_194df3105ad7148dcf2b98a91b5e727a=1547557715"
 ]
 
 Now I want to check how many of mongo's arrays are, what statement can be solved?

Add. count () after find (query criteria)