public static void addStock(Product[] products, Scanner sc) {
	int num=-1;
	System.out.println("How many values do you want to add: ");
	num = sc.nextInt();

	while(num < 0) {
		System.out.println("Please enter only positive values!");
		System.out.println("How many values do you want to add: ");
		num = sc.nextInt();
	}
	for(int i=0; i<index; i++) {
		products[i].addQuantity(num);
	}
}