class Stack<T>
{
    private T[] elements;
    private int index = 0;

    public Stack(int capacity)
    {
        elements = new T[capacity];
    }

    public void Push(T item)
    {
        elements[index++] = item;
    }

    public T Pop()
    {
        return elements[--index];
    }
}

public class Program
{
    public static void Main()
    {
        Stack<int> intStack = new Stack<int>(5);
        intStack.Push(1);
        intStack.Push(2);
        intStack.Push(3);
        Console.WriteLine(intStack.Pop());
        Console.WriteLine(intStack.Pop());

        Stack<string> stringStack = new Stack<string>(5);
        stringStack.Push("A");
        stringStack.Push("B");
        stringStack.Push("C");
        Console.WriteLine(stringStack.Pop());
        Console.WriteLine(stringStack.Pop());
    }
}