return [ [ 2, 3, 4, 5 ], [ 1, 5, 6, 3 ], [ 1, 2, 6, 7 ], [ 1, 7, 8, 5 ], 
  [ 1, 4, 8, 2 ], [ 2, 8, 7, 3 ], [ 3, 6, 8, 4 ], [ 4, 7, 6, 5 ] ];
