class MyStack<T> {
    protected Object[] stack;
    protected int size;
    protected int tos = -1;
    
    MyStack(T ...objs) {
        this.size = 16;
        this.stack = new Object[size];
        for (T obj: objs) {
            this.push(obj);
        }
    }
    
    public void push(T obj) {
        if (this.tos == this.size - 1) {
            Object[] newStack = new Object[2 * this.size];
            for (int i = 0; i < this.size; i++) {
                newStack[i] = this.stack[i];
            }
            this.stack = newStack;
            this.size = 2 * this.size;
        }

        this.tos++;
        this.stack[this.tos] = (Object)obj;
    }
    
    public T pop() {
        if (this.tos == -1) {
            throw new ArrayIndexOutOfBoundsException("no elements");
        }
        
        T elem = (T)this.stack[this.tos];
        this.tos--;
        return elem;
    }
    
    public int size() {
        return this.tos + 1;
    }
}

class Main {
    public static void main(String[] args) {
        MyStack<Integer> stack = new MyStack<Integer>();
        for (int i = 0; i < 50; i++) {
            stack.push(i);
        }
        
        while (stack.size() > 0) {
            System.out.println(stack.pop());
        }
    }
}