size = 12
front = 42
back = 86
42 0 1 2 3 4 5 6 7 8 9 -999 -999 -999 -999 -72 
42 0 1 2 3 4 5 6 7 8 9 -999 -999 -999 -999 -72 
42 0 1 2 4 5 6 -999 -72 
-999 -72 0 1 2 4 5 6 42