What --ar to put for 600 x 1800 px?

What aspect ratio do I need to put in midjourney settings? Can't find a answer after using Google.

submitted by /u/Guilty-Reserve9939
[link] [comments] https://www.reddit.com/r/midjourney/comments/1fqqfvq/what_ar_to_put_for_600_x_1800_px/