Because we're either going to be in this situation or we're going to be in that situation. Or you could say they're equal to 100%, either way. 100% and 1 are the same number. It's equal to 100%. So if we figure out the probability that everyone has the same birthday, we could subtract it from 100. So let's see, if we could just rewrite this. The probability that someone shares a birthday with someone else, that's equal to 100% minus the probability that everyone has distinct separate birthdays.