Or they don't have to be 0.5, but if 1 was 0.6, the other one would have to be 0.4. They have to add to 1. If one of these was, you can't have a 60% probability of getting a heads, and then a 60% probability of getting a tails as well, because then you would have essentially a 120% probability of either of the outcomes happening, which makes no sense at all. So it's important to realize that a probability distribution function, or probability distribution function in this case for a discrete random variable, they all have to add up to 1. It's 0.5 plus 0.5. And in this case, the area under the probability density function also has to be equal to 1. Anyway, I'm all out of time for now.