Splitting the lines into pairs and running those sums through leaves us with:
0 4 2 8 5 13 13 17 17
-1 3 7 12 14 16
-2 2 5 10 4 3 10 9 11 12 12 15 13 19 16 21 18 15 21
1 2 2 11 11 10 14 16 16
0 2 9
-1 -3 3 12 14 17
-2 8 7
-4 0 13 17
-5
1 5 3 1 4 6 9 17 19
4 18
0 6 15 20 22 18
6 6 14 13 19
5
7 3 17
8 18 19 20
5 16
15 16 15
15 12
11
21
At which point someone else is going to have to take over because I need to change some tapes and head off home. I may have another crack at this later if I get bored of GTA3 (HA! As if!).
Andy | 
