Given a name, turn that name into a perfect square matrix (nested array with the amount of arrays equivalent to the length of each array). 

You will need to add periods (`.`) to the end of the name if necessary, to turn it into a matrix. 

If the name has a length of 0, return `"name must be at least one letter"`

## Examples

"Bill" ==> [ ["B", "i"],
             ["l", "l"] ]

"Frank" ==> [ ["F", "r", "a"],
              ["n", "k", "."],
              [".", ".", "."] ]