private void Shopping(string buying)
{
string[] buyingArr = buying
.Split(" ", StringSplitOptions.RemoveEmptyEntries).ToArray();
string name = buyingArr[0].Trim();
string product = buyingArr[1].Trim();
if (name == "" || product == "")
{
Console.WriteLine("Name cannot be empty");
throw new ArgumentException();
}
Product productToBuy = products.Find(x => x.Name == product);
Person person = people.Find(x => x.Name == name);
person.BuyingProduct(productToBuy);
}