class TestThread extends Thread {
	String str;
public TestThread (String str) {
	this.str = str;
}

public void run() {
	for (;;)
		System.out.print (str);
}
}

class TestConcurrency {
public static void main (String Args[]) {
	new TestThread("A").start();
	new TestThread("B").start(); 	
}
}