Hmmm, evaluate:
1-4: 1 key, definately needed
1-8: one key, definately needed.
2-4: one key... I'm almost sure it is definately needed.
2-8: Fuzzy gray matter
3-4: No keys If I remember correctly.
3-8: No keys
4-4: 4 keys. All needed.
4-8: One keey. Needed.
5-4: Fuzzy gray matter. I don't think there were keys.
5-8: No keys
6-4: 2 keys, both needed.
6-8: no keys... except for door 2, and it is needed.
So, we're down to 2-8 and 5-4. That si before I check...
Bah! It's 2-4! There's a way to get to the exit without opening that door.
Congratulations! You have just been blessed by the wisdom of Steve.