---

class Array {
private:
    int size;
    int* data;

public:
    Array(int n = 0) {
        size = n;
        data = new int[size];
    }
    
    ~Array() {
        delete[] data;
    }
    
    int& operator[](int index) {
        return data[index];
    }
    
    int operator()(int left, int right, int h) {
        int sum = 0;
        for (int i = left; i <= right; i += h) {
            sum += data[i];
        }
        return sum;
    }
    
    friend istream& operator>>(istream& input, Array& v);
    friend ostream& operator<<(ostream& output, const Array& v);
};