Описание:
_________D_____________________________D__________________________
________DDD___________D______________DDD________________________
_______DDDDD_________DDD___________DDDDDD______________________
______DDDDDDD_______DDDDD_________DDDDDDD_____________________
_____DDDDDDDD______DDDDDD________DDDDDDDD_____________________
______DDDDDDD_______ DDDD_________DDDDDDD_____________________
_______ DDDD_________________________DDDD_______________________