using System;

using System.Collections.Generic;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        string json = "{'BTC':{'free':0.00737148,'used':0,'total':0.00737148},'LTC':{'free':0,'used':0,'total':0},'ETH':{'free':0.00043127,'used':0,'total':0.00043127}}";

        var data = JsonConvert.DeserializeObject<dynamic>(json);

        Console.WriteLine(data.BTC);

    }

}