Hand trace an initially empty stack X through the following operations:
X.push(new Integer(4));
X.push(new Integer(3));
Integer Y = X.pop();
X.push(new Integer(7));
X.push(new Integer(2));
X.push(new Integer(5));
X.push(new Integer(9));
Integer Y = X.pop();
X.push(new Integer(3));
X.push(new Integer(9));