Two Featured Image Sizes

Hey gang,

I’ve done a few thorough searches, and can’t quite solve this one. I am working on a child theme of Twentythirteen.

On the homepage, I want to have the first post formatted differently than the subsequent posts. (Temp Site Link) As you can see at the link, I’ve got a good start to this part.

What I can’t solve, however, is this: I want the first post’s Featured Image to be a completely different size than all the other posts. The First post I’d like to be 220×336, and the other posts be 175×190.

Any ideas?

Thanks!