using System;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        string json = @"

            {

              ""time"": {

                ""updated"": ""Feb 7, 2019 04:50:00 UTC"",

                ""updatedISO"": ""2019-02-06T22:50:00-06:00"",

                ""updateduk"": ""Feb 7, 2019 at 04:50 GMT""

              },

              ""disclaimer"": ""This data was produced from the CoinDesk Bitcoin Price Index (USD). Non-USD currency data converted using hourly conversion rate from openexchangerates.org"",

              ""bpi"": {

                ""USD"": {

                  ""code"": ""USD"",

                  ""rate"": ""3,398.5150"",

                  ""description"": ""United States Dollar"",

                  ""rate_float"": 3398.515

                },

                ""XBT"": {

                  ""code"": ""XBT"",

                  ""rate"": ""1.0000"",

                  ""description"": ""Bitcoin"",

                  ""rate_float"": 1

                }

              }

            }";

        var rate = (string) JToken.Parse(json).SelectToken("bpi.USD.rate");

        Console.WriteLine(rate);

    }

}