# Problem 166: Criss Cross
A 4x4 grid is filled with digits d, 0 ≤ d ≤ 9. It can be seen that in
the grid 6 3 3 0 5 0 4 3 0 7 1 4 1 2 4 5 the sum of each row and each
column has the value 12. Moreover the sum of each diagonal is also 12.
In how many ways can you fill a 4x4 grid with the digits d, 0 ≤ d ≤ 9 so
that each row, each column, and both diagonals have the same sum?