Call HTTP Web service workflow Action : Access JSON data in dictionary

I have an action "Call HTTP Web service Action" in my Sharepoint 2013 workflow. It works fine when one data is returned. But how do i refer dictionary items through index?

My JSON data is as follows:

[{"AccountID":342342342,"AgentName":"Tawanda Maddox","BframeCollectorID":783,"Call_Date":"/Date(1262329200000-0700)/","ID":1,"NobleID":1312},{"AccountID":4556875,"AgentName":"Michael Raimo","BframeCollectorID":526,"Call_Date":"/Date(1262329200000-0700)/","ID":2,"NobleID":4521},{"AccountID":54745465,"AgentName":"Michael Silver","BframeCollectorID":212,"Call_Date":"/Date(1262329200000-0700)/","ID":3,"NobleID":5246}]

How do i access this data? AgentName(0) is giving any result.

Thanks,

Avni Bhatt