I wanted to solve Unknown Language Round 4, but came across a weird "bridge operator" behaviour at the end of code line.

As the code is toroidal, next code would loop printing 1:

1.

Also, we can discover, that pop spawns 0 from the empty stack:

1..@

And the next code should print 1 and then loop printing 0, because # makes it to omit push(1):

1.#

But unfortunately, it loops printing 1. Because somehow codeforces's interpereter can't handle # crossing the end of code line. Actually, Wikipedia doesn't regulate it, nor Esolang does, but I think it is a bug.

Didn't find support email, so I post it here. Maybe someone would like to comment.