public abstract class main {
    public static void main(String [] args) {
        IntStackA s=new IntStack();
        IntStackA t=new intstack();
        s.push(2);  System.out.println("s="+s);
        s.push(5);  System.out.println("s="+s);
        t.push(7);  System.out.println("t="+t);
        s.push(3);  System.out.println("s="+s);
        System.out.println(s.pop());  System.out.println("s="+s);
        s.push(4);  System.out.println("s="+s);
        System.out.println(s.pop());  System.out.println("s="+s);
        System.out.println(t.pop());  System.out.println("t="+t);
        System.out.println(s.pop());  System.out.println("s="+s);
        System.out.println(s.pop());  System.out.println("s="+s);
        
    }
}