using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Diagnostics;

using System.IO;

using System.Threading;

using System.Collections.ObjectModel;

using System.Reflection;

using System.Runtime.Serialization;

using System.Data;

using System.ComponentModel;

using System.Globalization;

using System.Runtime.Serialization.Formatters.Binary;

using System.Collections.Specialized;

using System.Web.Routing;

using System.Net.Mail;

using System.Runtime.InteropServices;

using System.Text.RegularExpressions;

using System.Net;

using System.Runtime.Serialization.Formatters;

//using System.Net.Http;

using System.Threading.Tasks;

​

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Converters;

using Newtonsoft.Json.Serialization;

using System.Web.SessionState;

​

// https://stackoverflow.com/questions/42918284/deserialize-json-c-sharp-error

​

    public class Valores

    {

        [JsonProperty("nome")]

        public string Nome { get; set; }

        [JsonProperty("valor")]

        public double Valor { get; set; }

        [JsonProperty("ultima_consulta")]

        public int UltimaConsulta { get; set; }

        [JsonProperty("fonte")]

        public string Fonte { get; set; }

    }

​

    public class RootObject

    {

        public RootObject() { this.valores = new Dictionary<string, Valores>(); }

        public bool status { get; set; }

        public Dictionary<string, Valores> valores { get; set; }

    }

​

    public class TestClass

    {

        public static async Task<RootObject> GetAsync()

        {

            using (var client = new WebClient())

            {

                client.Headers["User-Agent"] = "something";

                var json = await client.DownloadStringTaskAsync(@"http://api.promasters.net.br/cotacao/v1/valores");

                var root = JsonConvert.DeserializeObject<RootObject>(json);

                return root;

            }   

        }

        public static void Test()

        {

            var valores = TestClass.GetAsync().Result;

            Console.WriteLine("Downloaded, deserialized and reserialized {0}:", valores);

            Console.WriteLine(JsonConvert.SerializeObject(valores, Formatting.Indented));

        }

    }

​

    public class Program

    {

        public static void Main()

        {

            TestClass.Test();

        }

    }

​