Stack Improved

#include <iostream>
#include <cstdlib>

using namespace std;

class Stack{
    private:
        int *arr;
        int top;
        int size;
    public:
        Stack();
        Stack(int);
        ~Stack();
        void push(int);
        int pop();
};

Stack::Stack(){
    top = -1;
    size = 100;
    arr = new int[size];
}

Stack::Stack(int size){
    top = -1;
    this->size = size;
    arr = new int[this->size];
}

Stack::~Stack(){
    delete[] arr;
}

void Stack::push(int item){
    if(top == (size - 1)){
        cout << "STACK OVERFLOW" << endl;
    }
    else{
        top = top + 1;
        arr[top] = item;
        cout << item << " pushed" << endl;
    }
}

int Stack::pop(){
    int ret  = -1;
    if(top == -1){
        cout << "STACK UNDERFLOW" << endl;
    }
    else{
        ret = arr[top];
        top = top - 1;
    }
    return ret;
}

int main() {
    system("cls");
    int size;
    cout << "Enter the size of the stack: ";
    cin >> size;
    Stack obj(size);
    int choice;
    do {
        cout << "Press 1 to push an element\n";
        cout << "Press 2 to pop an element\n";
        cout << "Press 3 to quit\n";
        cout << "Enter your choice: ";
        cin >> choice;
        int temp;
        switch(choice){
            case 1:
                cout << "Enter item: ";
                cin >> temp;
                obj.push(temp);
                break;
            case 2:
                temp = obj.pop();
                if(temp != -1)
                    cout << temp << " popped" << endl;
                break;
            case 3:
                break;
            default:
                cout << "Invalid choice" << endl;
        }
    }while(choice != 3);
    return 0;
}