using System;
using System.Net;
using System.Net.Http;

public class Program
{
    public static void Main()
    {
        HttpClient client = new HttpClient();
        
        try
        {
            HttpResponseMessage response = client.GetAsync("https://example.com").Result;
            
            if (response.StatusCode == HttpStatusCode.ServiceUnavailable)
            {
                Console.WriteLine("服务不可用，请稍后重试。");
            }
            else
            {
                // 处理其他状态代码
                Console.WriteLine("请求成功。");
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine("发生异常：" + ex.Message);
        }
    }
}