return [ [ 2, 3, 4, 5 ], [ 1, 5, 6, 3 ], [ 1, 2, 7, 8 ], [ 1, 8, 9, 10 ], 
  [ 1, 10, 11, 2 ], [ 2, 11, 12, 7 ], [ 3, 6, 13, 14 ], [ 3, 14, 15, 4 ], 
  [ 4, 15, 16, 17 ], [ 4, 17, 18, 5 ], [ 5, 18, 19, 6 ], [ 6, 19, 20, 13 ], 
  [ 7, 12, 21, 14 ], [ 7, 13, 15, 8 ], [ 8, 14, 21, 9 ], [ 9, 21, 20, 22 ], 
  [ 9, 22, 18, 10 ], [ 10, 17, 19, 11 ], [ 11, 18, 22, 12 ], 
  [ 12, 22, 16, 21 ], [ 13, 20, 16, 15 ], [ 16, 20, 19, 17 ] ];
