public abstract interface MyList {

    public abstract void add(int x);
    public abstract int remove();
    public abstract boolean isEmpty();
    public abstract int getSize();
}

class MyStack implements MyList {
    private int[] arr;
    private int size;

    public MyStack(int x)
    {
        arr= new int[x];
        size=0;
    }

    public void add(int x)
    {

            if (size == arr.length)
                resize();
            arr[size] = x;
            size++;


    }

    public void resize()
    {
        int[]arr2=new int[arr.length*2];
        for(int k=0;k<arr.length;k++)
        {
            arr2[k]=arr[k];
        }
            arr=arr2;
    }

    public int remove()
    {

        if (size==0)
            return -999;

        return arr[size--];
    }

    public boolean isEmpty()
    {
        return size==0;
    }

    public int getSize(){
        return size;
    }
    public String toString()
    {

        String ret="[";
        for(int k=size-1;k>-1;k--)
        {
            if (k==0) {
                ret = ret + arr[k] + "]";
                break;
            }
            ret= ret + arr[k] + ", ";
        }
        return ret;
    }



}

class MyQueuee implements MyList{
    private int[] arr;
    private int size;
    private int front;
    private int back;

    public MyQueuee(int x)
    {
        arr=new int[x];
        size=0;
        front=0;
        back=0;

    }

    public void add(int x)
    {
        if(back==arr.length)
            resize();
        size++;
        arr[back]=x;
        back++;
    }

    public void resize()
    {
        int[]arr2=new int[arr.length*2];
        for(int k=0;k<arr.length;k++)
        {
            arr2[k]=arr[k];
        }
        arr=arr2;
    }

    public int remove()
    {
        if (front==arr.length)
            return -999;
        size--;
        return arr[front++];
    }

    public boolean isEmpty()
    {
        return size==0;
    }

    public int getSize(){
        return size;
    }

    public String toString()
    {
        String ret="[";
        for(int k=front;k<back;k++)
        {
            if (k==back-1) {
                ret = ret + arr[k] + "]";
                break;
            }
            ret= ret + arr[k] + ", ";
        }
        return ret;
    }

}