The letters W, X, Y and Z are to appear twice in every row and column and once in every 2x2 box.

From the given starters, can you finish the puzzle?

X | | | | W | | W | | |

| W | Y | | | Y | | | |

| | | | | | | Z | |

| X | X | | | W | | | |

Z | | W | | W | | | Z | |

| | | Y | | | | | |

| | | | | | | Y | |

| X | W | | | Y | X | | |

The completed arrangement is as follows:

x..y z..x w..z w..y

z..w y..w x..y z..x

w..z y..w y..x x..z

y..x x..z z..w y..w

z..y w..x w..x y..z

x..w z...y y..z w..x

w..z x..y x..w z..y

y..x w..z z..y x..w