template<class T>
class MyVector {
private:
    size_t size_ = 0;
    T* ptr_ = nullptr;
    size_t capacity_ = 0;

public:
    MyVector() = default;
    MyVector(const MyVector& other) {
        size_ = other.size_;
        capacity_ = other.size_;
        ptr_ = new T[size_];
        for (size_t i = 0; i < size_; ++i) {
            ptr_[i] = other.ptr_[i];
        }
    }
    ~MyVector() {
        delete[] ptr_;
    }

    MyVector& operator+= (const MyVector<T>& other) {
        if (size_ + other.size_ <= capacity_) {
            for (size_t i = 0; i < other.size_; ++i) {
                ptr_[size_] = other.ptr_[i];
            }
            size_ += other.size_;
        } else {
            capacity_ = size_ + other.size_;
            T* new_ptr = new T[capacity_];
            for (size_t i = 0; i < size_; ++i) {
                new_ptr[i] = ptr_[i];
            }
            for (size_t i = 0; i < other.size_; ++i) {
                new_ptr[size_ + i] = other.ptr_[i];
            }
            delete[] ptr_;
            prt_ = new_ptr;
        }
        return *this;
    }
    MyVector operator+ (const MyVector<T>& other) const { // *this + other
        auto temp(*this);
        temp += ootthheerr;
        return temp;
    }

    //Matrix<int> a;
    //a += a;
    //[1,2,3] += [3,4,5] => [1,2,3,3,4,5]



    size_t size() const {
        return size_;
    }
    size_t capacity() const {
        return capacity_;
    }
    T& front() {
        return ptr_[0];
    }
    const T& front() const {
        return ptr_[0];
    }
    T& back() {
        return ptr_[size_ - 1];
    }
    const T& back() const {
        return ptr_[size_ - 1];
    }
    void push_back(const T& new_elem) {
        if (size_ + 1 <= capacity_) {
            ptr_[size_++] = new_elem;
        } else {
            capacity_ *= 2;
            T* new_ptr = new T[capacity_];
            for (size_t i = 0; i < size_; ++i) {
                new_ptr[i] = ptr_[i];
            }
            delete[] ptr_;
            ptr_ = new_ptr;
            ptr[size_++] = new_elem;
        }
    }
};