: :
- 4 ()
 
/ 
 
 
 
-13 1...X
-31 3...X
-40 4...X
-13 1...X
-22 2...X
-31 3...X
-40 4...X
-131...X
-22 ()2...X
-22 ()2...X
-31 ()3...X
-40 ()4...X
-13 ()1...X
-13 1...X
-22 2...X
-31 3...X
-131...X
-22 ()2...X
-31 ()3...X
-40 ()4...X
-40 ()4...X
-1311...X
-1321...X
-22 ()2...X
-22 ()2...X
-31 ()3...X
-31 ()3...X
-40 ()4...X
-40 ()4...X