gistfile1.txt

db.areas.aggregate(
   [
      {
         $project: {
            areaId: 1,
            numberOfResource: { $size: "$resources" }
         }
      }
   ]
)

gistfile2.txt

var max=0;
db.areas.find().forEach(function(obj) {
    var curr = Object.bsonsize(obj); 
    if(max < curr) {
        max = curr;
    } 
})
print(max);