class vector {
private:
    int* data;
    int size;
    int capacity;

    void resize() {
        int newCapacity = 2 * capacity;

        int* newData = new int[newCapacity];

        for (int i = 0; i < capacity; i++)
            newData[i] = data[i];

        delete[] data;
        data = newData;

        capacity = newCapacity;
    }

    void copy(const vector& other) {
        data = new int[other.getCapacity()];

        for (int i = 0; i < other.size; i++)
            data[i] = other.data[i];

        size = other.size;
        capacity = other.capacity;
    }

    void free() {
        delete[] data;
    }

public:
    vector() : data(new int[8]), size(0), capacity(8) {}

    vector(const vector& other) {
        copy(other);
    }

    vector& operator=(const vector& other) {
        if (this != &other) {
            free();
            copy(other);
        }
        return *this;
    }

    int getSize() const {
        return size;
    }

    int getCapacity() const {
        return capacity;
    }

    void push_back(int& val) {
        if (size == capacity)
            resize();
        data[size++] = val;
    }

    int operator[](int arg) const {
        if (arg < 0 || arg >= size)
            throw std::exception("out of bound");
        return data[arg];
    }

    ~vector() {
        free();
    }
};