JAVA账号密码问题

import java.util.Scanner;
public class Yy {
    public static void main(String[] args) {
        String s = "123456789";
        String d = "123456";
        int cishu = 0;


        while (cishu < 3) {

            Scanner zhanghao = new Scanner(System.in);
            System.out.println("请输入用户名：");
            String a = zhanghao.next();
            Scanner mima = new Scanner(System.in);
            System.out.println("请输入密码：");
            String b = mima.next();

            if (!s.equals(a) || d.equals(b)) {
                cishu++;
                if (cishu <= 2)
                    System.out.println("用户名或密码错误！");
            }
            if (s.equals(a) && d.equals(b)) {
                System.out.println("登陆成功！");
                break;
            }
        }

        if (cishu == 3)

            System.out.println("登录失败，无法登录！");
    }
}