A question about punctuation in two sentences

Hello. I was doing a test and encountered two sentenes:

1. While I was walking in the country it began to snow.

2. When I arrived there Sam had already left.

I'd like to know if any commas are necessary in these sentences. Personally, I think there should be a comma after "country" in the first sentence and after "there" in the second but in the answer sheet the sentences were just like I've written them here (without any commas), so I'm unsure.

Thanks.