Probably somewhere between about 2 and 1,000.
My utilitarian side pushes me towards the 2 - but my pragmatic will for self-preservation might not let that happen. On the other hand, with a number over 1,000 or so, I'm fairly sure the utilitarian side would win.
It's very hard for me to narrow it down more that that, since I don't have any more information about who might be in the other room. A lot of my answer depends on how much I know about the other room - were they randomly chosen? Who are they? Prisoners? Politicians? Lawyers? Doctors? Heads of State? Librarians? Americans? My family?
If you want to force me to say a single number, I'll go with 200. But I don't promise to stick to it.