import java.util.*;

class Demo {
  public static void main(String[] args){
    Vector x, y;
    x = new Vector();
    y = new Vector();
    x.addElement(new Integer(3));
    x.addElement(new Integer(4));
    y = x;
    y.setElementAt(new Integer(7), 0);
    System.out.println(x.elementAt(0));
  }
}