using System;

using Newtonsoft.Json;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        string json = @"{

  ""1"" : ""abc"",

  ""2"" : ""def""

}";

​

       var m = JsonConvert.DeserializeObject<Dictionary<long, string>>(json);

        Console.WriteLine(m.Count);

        Console.WriteLine(m[2]);

    }

}