When I try to update a price option it tells me that it has to be positive

In the options of a radio button it had a negative price. The discount was displayed in my cart. When I went to change the text of the radio button field option it told me that the quantity has to be 0 or greater than 0. Before it let me enter negative quantities. What happens when I want to make a discount, from a radio button option, instead of raising the price?