Sokoban Level 3b

This sokoban level has 13 boulders and 10 holes. The upper center part is probably the hardest 0 boulder ^ pit @ starting position/downstairs < upstairs

|........|...|.....| |.00..-00|.-.|.....| |..|.0.0.|00.|.....| |-.|..-..|.-.|..<..| |...--.......|.....| |...|.0.-...-|.....| |.0.|0.|...--|.....| |-0.|..---+| |..0....^^^^^^^^^^.| |...|.@-

Strategy
The following solution solves the level without putting any blocks in an immobile position. Faster solutions which do not leave every boulder free exist.

All boulders are replaced by letters so they can be referred to. Moving the boulders is shortened to r for right, l for left, u for up, d for down. An asterisk is used to denote the last move filled a pit (and thus removed the boulder from the game). So Nddrr* means move boulder N two times down and two times to the right into a pit. |........|...|.....| |.AB..-CD|.-.|.....| |..|.E.F.|GH.|.....| |-.|..-..|.-.|..<..| |...--.......|.....| |...|.I.-...-|.....| |.J.|K.|...--|.....| |-L.|..---+| |..M....^^^^^^^^^^.| |...|.@- Clear the lower left, make sure you move J to the right and do L before J. Mlrrrrrr* Jr Ldrrrrrrr* Jddrrrrrrr* Clear A and B. Adddddddrrrrrrrrr* Bldddddddrrrrrrrrrr*

|........|...|.....| |.....-CD|.-.|.....| |..|.E.F.|GH.|.....| |-.|..-..|.-.|..<..| |...--.......|.....| |...|.I.-...-|.....| |...|K.|...--|.....| |-..|..---+| |..........@.^^^^^.| |...|.>-

Clearing the top room is probably the hardest part of the level. Pushing E up and enter the top room by moving D down, so you can remove F and then E. Eu Ddd Flllu Ed Frrdddddddrrrrrrrrrrr* Erurrdddddddrrrrrrrrrrrr* Cdrrrurrdddddddrrrrrrrrrrrrr*

|........|...|.....| |.....-..|.-.|.....| |..|.....|GH.|.....| |-.|..-.D|.-.|..<..| |...--.......|.....| |...|.I.-...-|.....| |...|K.|...--|.....| |-..|..---+| |.............@.^^.| |...|.>- Fill the last two holes with I and K. Idddrrrrrrrrrr* Kddlllrrrrrrrrrrrrrrr*

|........|...|.....| |.....-..|.-.|.....| |..|.....|GH.|.....| |-.|..-.D|.-.|..<..| |...--.......|.....| |...|...-...-|.....| |...|..|...--|.....| |-..|..---+| |.................@| |...|.>-