And we don't care about the order. So let's take a look at all the four potential outcomes. We can either get a boy and a boy, which is not what we want. We can either get a girl and a girl, which is also not what we want, but the other two outcomes are boy and a girl and girl and a boy. And in both of these cases, we basically get one girl and one boy. Now, these two events are mutually exclusive.