Appending a variable to filename

Hi, I'm very new to MAX/MSP/Jitter (I've just taken a 3 day crash course about Jitter, because I am mailny interested in video).
I'm trying to load a random movie each time I open my patch. I used a [random] object linked to a [sel] and then a read message for each movie. Since I use only 5 movies it's easy to get the thing working but if I'd like to use 100 different random movies it would be a mess to use this system.
I was thinking about a [random] object linked directly to the read message: if my movie names are "movie_0.mov", "movie_1.mov" etc... my read message could be something like read movie_$1.mov where $1 is the number gerated by my random object...
How can I achieve that?
Thanks