为什么这个异常捕获机制没有起作用？

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _01第四天学习
{
    class Program
    {
        static void Main(string[] args)
        {
             Console.WriteLine("请输入您的QQ号：");
              string QQ = Console.ReadLine();
             Console.WriteLine("请输入你的密码：");
              string mima = Console.ReadLine();
            try
            {
                if (QQ == "19045584" && mima == "654321")
                {
                    Console.WriteLine("登录成功！");
                }
            }
            catch {
                Console.WriteLine("用户名与密码不符，请重新输入，谢谢合作！");
            }
            Console.ReadKey();
        }
    }
}
请各路大虾指点！！！