 So to start, one of the things I want to do is just go over just how we're dealing with extracting out our numbers. Let's say for example, we take the code that we are being given, and I just put that in. So now I have card. So how do I start to extract out every single number? Well, just like in the last video, we said that the card basically had all of these letters stored, or all these digits stored in a specific location. We started counting at zero, which was interesting because I was just like, oh, yeah, you know, that's what computer do. But what I'm able to do is I'm actually able to say card, for example. And if I put square bracket zero, square bracket, that'll actually allow me to extract out individual cards. This is pretty nice because if we're thinking about needing to cycle through things, let's say for example, while, well, index equaling something like 15, I don't know, that seems like an odd number, maybe the furthest away number. And I did card at index, oh, well, I'm getting four, again, I'm getting this four this time. Well, if I did something like while index is greater than zero, maybe I print card at index. And then I make my index go down by two. Suddenly, I've extracted out all of my odd numbers and maybe I run a running total on those things. Maybe that might be a little bit of a benefit. Maybe if I changed it, maybe I change this to 14, maybe I take that same algorithm. That seems to be giving me my even numbers and I happen to know math. Oh, remember, you'd have to convert this into something like an integer before you got to do any sort of math to it, but there's that time thing to affect that we need to worry about, say for example, why don't you? Oh, that's why. There's how I get my 18s and my 16s and all of those things. So all right, it doesn't seem like it's that daunting of a task. One other little note, since we do kind of have to go through it, if we go all the way down to this is valid card, notice people always seem to forget this portion right here. String must be 13 to 16 digits. How can I find that out? Well, I know card and we've talked about Lynn before, Lynn card. That's how I find that 16. So suddenly all these little pieces, parts that we've worked on in the past can start to come together. My recommendation, start up top. This part. We don't need to deal anything with that, but get company. Well, I just talked about how we need to get that first portion using the index. Only I remembered how I could find that out. Maybe I make an if statement that checks those and get digit. Get digit, remember, is going to handle things a little differently. Get digit is getting a number, not a string, not a string. It's a five, just a normal five. You want to double that number and look at it and see what we need to do there. Double even place. Nothing terribly crazy there. If you watch the previous video, you should kind of understand what that's going to be doing and how this stuff right here that I am going to just leave on the screen for a second as I stare at you and you pause the video recording all of it, works its magic. Same with odd place. Maybe you do odd place first. It's going to be a little easier because all you're doing is running total and you're not trying to double any digits. Then finally, is valid. Take everything that we've tied in together, plug it into here and tell me whether or not the card that I've typed in or the card that is given to you is true.