We write down our pluses and negatives. So at a PH of 3.5, this will be negative because this value is lower than this. So we have a negative here, we have a positive value here. And for these particular groups, we're going to have a neutral charge because this PH is below 4.1. And that means these will gain an H atom at a PH of below this. So we have a positive, a negative and two neutral.