D DDD DDD D DDD DD DDDDDDD DD DDD DD D DDD DDD D DDD:

X+D = XD

:+D = :D

D+: = D:

D+X = DX

DD DDDDD DDD DD DDDDD DDD DDD DDD DDD DDD DDDDD DDD DDDDD DDD DDD DDDDDD DDDD DD DDDD DDDD DDDD DDDD!