Zero.
1) He tied the rope onto the next cell down or got one of the cell mates to hold it
2) Split the rope is half and tied one end to the other.
Decs your second answer is right he split the rope in half making it slimmer but twice the length.
ill edit in another question when i think of one
The rope might not be strong enough in two.
Another room question.
There is a room with no doors/windows. It has four walls, a ceiling and a floor. There is a bench and a mirror in the room. How do you escape?
Hint: There is no hole behind the mirror.
Alice in Wonderland

Step through the looking glass!!!

^____^
Not quite but you have the right idea.
Edit: Anybody else care to try?
er...DAMN i remember this question my friends told me the answer, something about cutting the mirror in half, and put one half with another and you get a hole and crawl through the hole or something??
Yeah but it also involves the bench.
The answer is:
Look in the mirror. See what you saw. Use the saw to cut the bench in half. Two halves make a whole. Jump through the hole.

HA! i knew it had something to do witha saw, but i forgto how he got the saw.. lol
When I first heard that one I absolutely hated it but it kind of grew on me I guess.