import java.util.*;
/**
*
*/
/**
* @author CCD
*
*/
public class MyStack {
private ArrayList elementData = new ArrayList();
private Object[] Myelement = elementData.toArray();
private int Length = elementData.size();
public void push(Object E){
Myelement[++Length] = E ;
}
public Object pop(){
int NowLength = size()-1;
Object obj = peek();
Length--;
Myelement[Length] = null ;
return obj;
}
public Object peek(){
int NowLength = size();
if(NowLength == 0)
throw new EmptyStackException();
NowLength -= 1 ;
if(NowLength >= Length )
throw new ArrayIndexOutOfBoundsException(NowLength + " >= " + Length);
return Myelement[NowLength];
}
public boolean isEmpty(){
return size() == 0;
}
public int size(){
return Length;
}
}