Replying to 50mm or 35mm

Hi all,

Forgive my ignorance - and the fact that I'm sure some of you will have answered this question many times before - but which lens should I buy: 35mm or 50mm?

I'm going to Japan and will be working with a team of guides - so with this in mind, I'm putting together a small kit so that I can properly document my trip and my time on the hill. I work with a Nikon 5100.

In addition to some other lenses I'm looking at, I'd like a fixed prime. Could anyone advise?

Thanks guys,
Faith