import java.util.*;
import java.lang.*;

public class StackVector {
// Implement our stack for the operators	
	protected Object[] v;
	int capacity;
	int TAIL=0;
	
	public StackVector () {
		 this.capacity = 10000;
		 v=new Object[capacity];
	}
	public void push(Object o){
	    v[TAIL]=o;
		TAIL=(TAIL+1);
	}
	public Object pop(){
	    Object q=v[TAIL-1];
		TAIL = TAIL-1;
		return q;
	}
	public Object peek(){
		return v[TAIL-1];
	}
	public boolean isEmpty(){
	   if(this.getSize()==0) return true;
	   else return false;
	}
	public int getSize(){
	    int size = TAIL;
		return size;
	}
	public Object getElementAt(int i){
	    return  v[i];
   }
	    
}