#include <iostream>

using namespace std;

class Array {
private:
    int* array;
    int length;
public:
    Array();
    Array(int* array, int length);
    Array(int length, int value = 0);
    ~Array();
    Array& operator = (const Array& a);
    friend ostream& operator<<(ostream& o, const Array& a);
    Array& operator += (int element);
    Array& operator -- ();
    Array operator -- (int);
};

Array::Array() {
    this->array = new int;
    *this->array = 0;
    this->length = 1;
}

Array::Array(int *array, int length) {
    this->length = length;
    this->array = new int[this->length];
    for(int i = 0; i < length; i++) {
        this->array[i] = array[i];
    }
}

Array::Array(int length, int value) {
    this->length = length;
    this->array = new int[this->length];
    for(int i = 0; i < length; i++) {
        this->array[i] = value;
    }
}

Array::~Array() {
    delete [] this->array;
}

Array& Array::operator=(const Array &a) {
    if(this == &a) {
        return *this;
    }
    delete [] this->array;
    this->length = a.length;
    this->array = new int[a.length];
    for(int i = 0; i < this->length; i++) {
        this->array[i] = a.array[i];
    }
    return *this;
}

ostream& operator<<(ostream &o, const Array &a) {
    for(int i = 0; i < a.length; i++) {
        o << a.array[i] << " ";
    }
    o << endl;
    return o;
}

Array& Array::operator--() {
    int* temp = new int[this->length - 1];
    for(int i = 1; i < this->length; i++) {
        temp[i - 1] = array[i];
    }
    delete [] this->array;
    this->length--;
    this->array = temp;
    return *this;
}

Array Array::operator--(int) {
    Array old = Array(this->array, this->length);
    int* temp = new int[this->length - 1];
    for(int i = 1; i < this->length; i++) {
        temp[i - 1] = array[i];
    }
    delete [] this->array;
    this->length--;
    this->array = temp;
    return old;
}

Array& Array::operator+=(int element) {
    int* temp = new int[this->length + 1];
    for(int i = 0; i < this->length; i++) {
        temp[i] = this->array[i];
    }
    temp[this->length] = element;
    this->length++;
    delete [] this->array;
    this->array = temp;
    return *this;
}

int main() {
    int arr1[] = {3, 5, 7, 9};
    Array ar1 = Array();
    Array ar2 = Array(arr1, sizeof arr1 / sizeof (int));
    Array ar3 = Array(5);
    Array ar4 = Array(3, 4);
    Array ar5;
    ar5 = ar2;
    cout << ar1;
    cout << ar2;
    cout << ar3;
    ar2 += 21;
    --ar1;
    cout << ar1;
    cout << ar2;
    return 0;
}