What is the possibility of me getting pregnant if he finished inside me a couple days before my period starts?

---I know there is still a possibility. I should probably clarify that because a lot of you think I don't know that. I do. What I meant was, what are the chances? Like how high is the probability of it? I know having unprotected sex isn't the best idea and letting him finish inside me isn't either but it happened. Y'all can stop telling me not to do that/let that happen unless you're going to give an actual answer to my question. Please and thank you.