public class StackTest { public static void main(String［］ args) { Stackst = new Stack(); st.push(new Integer(11)); st.push(new Integer(22)); st.push(new Integer(33)); System.out.println("size is-> "+st.size()); System.out.println("Top is-> "+st.peek()); st.pop(); System.out.println("new Top is-> "+st.peek()); } } 程序运行的结果是 size= ( )。