On the 17 day of Christmas, my true love gave to me:
Hikaku Harmony
How to play Hikaku
Santa needs you to fill the grid so that every column and every row contains the digits 1 to 5, also obeying the 'less-than' (<) and 'greather-than' (>) operators between the cells. If there is a straight line between two cell, one does not know which cell contains the greather number.
