That's 50 separate codes, not 1 long code. Try one at random.

Sorry about that - I edited the list for clarity. http://xkcd.com/208/

After frustrating 10 minutes of entering codes, I realized that I started 4 hours too late.

That list must have been exhausted unbelievably fast, I don't think even Linode VPS giveaway a few months back was that successful.