return [ [ 2, 3, 4, 5 ], [ 1, 5, 6, 7 ], [ 1, 7, 8, 9 ], [ 1, 9, 10, 5 ], 
  [ 1, 4, 11, 2 ], [ 2, 11, 12, 7 ], [ 2, 6, 12, 3 ], [ 3, 12, 10, 9 ], 
  [ 3, 8, 10, 4 ], [ 4, 9, 8, 11 ], [ 5, 10, 12, 6 ], [ 6, 11, 8, 7 ] ];
