-- Empty: 3x3 -- 4x4 -- 5x5 -- 6x6* -- 7x7 -- 8x8 -- 9x9 -- 10x10**
Enter ABC... and 123... per cell, so that no letter or number repeats in a row or column, and that the combination is unique in the grid.
* = 6x6 Eulero is not possible -- ** = long believed impossible, use 0-9