typedef struct __stack
{
    struct __stack *next;
    int value;
}stack;

class Stack
{
    public:
    Stack();
    void Push(int value);
    void Pop(void);
    void Print(void);
    void Read(int pos);
    void Write(int pos,int value);
    int Size(void);
    void Delete(void);
    private:
    stack *p;
};

Stack::Stack(void)
{
    p=new stack;
    p->value=0;
    p->next=NULL;
}


void Stack::Push(int value)
{
    stack *ptr=p;
    while(ptr->next!=NULL)
        ptr=ptr->next;
    ptr->next=new stack;
    ptr=ptr->next;
    ptr->value=value;
    ptr->next=NULL;
}

void Stack::Pop(void)
{
    stack *ptr=p,*prev=p;
    while(ptr->next!=NULL)
    {
        prev=ptr;
        ptr=ptr->next;
    }
    if(ptr!=p)
    {
        delete ptr;
        prev->next=NULL;
    }
}

void Stack::Print(void)
{
    stack *ptr=p;
    ptr=ptr->next;
    while(ptr!=NULL)
    {
        cout << ptr->value << "\t";
        ptr=ptr->next;
    }
    cout <<"\n";
}

void Stack::Read(int pos)
{
    stack *ptr=p;
    int i;
    pos++;
    if(pos>0)
    {
        for(i=0;i<pos;i++)
            if(ptr->next!=NULL)
                ptr=ptr->next;
        cout << ptr->value <<endl;
    }
}

void Stack::Write(int pos,int value)
{
    int i;
    stack *ptr=p;
    pos++;
    if(pos>0)
    {
        for(i=0;i<pos;i++)
            if(ptr->next!=NULL)
                ptr=ptr->next;
        ptr->value=value;
    }
}

int Stack::Size(void)
{
    int i=1;
    stack *ptr=p;
    while(ptr->next!=NULL)
    {
        ptr=ptr->next;
        i++;
    }
    return i;
}

void Stack::Delete(void)
{
    stack *ptr=p,*prev=ptr;
    while(ptr->next!=NULL)
    {
        ptr=p;
        prev=ptr;
        while(ptr->next!=NULL)
        {
            prev=ptr;
            ptr=ptr->next;
        }
        if(ptr!=p)
        {
            delete ptr;
            prev->next=NULL;
        }
        ptr=p;
    }
}