public class MyThread extends Thread {

    public static void main(String[] args) throws InterruptedException {
        A a=new A();
        B b=new B();
        a.start();
        a.join();
        b.start();

    }
}
class A extends Thread{

    public void run(){
        for(int i=0;i<10000;i++){
            System.out.print("A   "+i);
        }
    }
}

class B extends Thread{

    public void run(){
        for(int i=0;i<10000;i++){
            System.out.print("B   "+i);
        }
    }
}