L = 10000;
M = 10;
spot = [| 
123, 134 |
890, 1231 |
1321, 3123 |
3333, 4444 |
9999, 10000 |
8888, 9988 |
4555, 4666 |
5000, 6000 |
8007, 8887 |
6777, 8000 |];