using System;

using System.Collections.Generic;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        var json = "{\"response\":[{\"id\":269058571,\"first_name\":\"Name\",\"last_name\":\"LastName\",\"photo_50\":\"http://cs624717.vk.me/v624717571/21718/X8.jpg\"}]}";

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

        foreach(var item in obj.response) {

            Console.WriteLine(item.first_name);

        }

    }

}

​

​

class RootObject

{

    public List<Item> response { get; set; }

}

class Item

{

    public string first_name { get; set; }

    public string last_name { get; set; }

    public string domain { get; set; }

    public string photo_50 { get; set; }

}