Interesting moving problem in Java

Move the containers on the ship

I get stuck every time with two containers left in the harbor.

B = big crane
M = medium crane
S = small crane
AR = All the way Right
AL = All the way Left

BAR,MAR,BAL,MAR,BAR,SAR,BAL,SAR,
MAL,BAR,MAL,SAR,MAR,BAL,MAR,BAR, ???


Whim