title: MongoDb Count after aggregation C# 2.0 driver
body: <p>I have the following aggregation pipline  </p>
  
  <pre><code>var count = dbCollection.
  Aggregate(new AggregateOptions { AllowDiskUse = true }).Match(query).
  Group(groupby).
  ToListAsync().Result.Count();
  </code></pre>
  
  <p>And this gets the following result: </p>
  
  <pre><code>{
      "result" : [ 
          {
              "_id" : {
                  "ProfileId" : ObjectId("55f6c727965bb016c81971ba")
              }
          }, 
          {
              "_id" : {
                  "ProfileId" : ObjectId("55f6c727965bb016c81971bb")
              }
          }
      ],
      "ok" : 1
  }
  </code></pre>
  
  <p>But it seems it will make count operation on client, but how to perform it in <code>MongoDb</code> ?
  I have <code>MongoDb 2.0 C# driver</code> &amp; <code>MongoDb v. 3.0.2</code></p>