Input:
------

40 23
########################################
#~      ~ ~~  ~  ~ ~~   ~ ~~    ~ ~ ~~ #
#~~ ~          ~~   ~   ~ ~~         ~ #
#~# ~~   ~~~~      ~  ~~~~  ~    ~~~  ~#
# ~        ~   ~ ~~ #~~       ~        #
#~~  ~~~   ~ ~ ~      ~ ~~ ~  ~  ~  ~  #
#     ~~  ~  ~ ~ ~~~       H    ~  #~  #
#  O~  ~  #  ~~~ ~      ~ ~~  ~  ~ ~~  #
#       ~ ~H~~   ~~ ~ #        ~~   ~  #
# ~~         ~ ~~~  ~~   ~~~~      ~  ~#
#~  ~    ~~~  ~   ~        ~   ~ ~~  ~~#
#     ~      # ~ ~~  ~~~   ~ ~ ~ #    ~#
#~ ~ ~~  ~  ~   H     ~~  ~~ ~ ~ ~~~   #
#       ~   ~   ~   ~  ~     ~~~ ~     #
# ~~  ~  ~ ~~   ~       ~ ~ ~     ~    #
#      ~~   ~   ~  ~         ~      ~~ #
#~ ~     #    ~~~~  ~    ~~~H   # ~    #
#  ~   ~ ~   ~        ~          ~~  ~ #
#  ~   ~     #~  ~   ~~  ~  ~         ~#
# ~~ ~ ~  ~~                ~   ~      #
#    ~~~        ~ ~~  ~  ~  ~   ~      #
# ~ ~     ~            ~~   ~   ~  ~   #
########################################
RRRUWWWRRRURWWWWRDRRWWRDWWWWD

Output:
-------
8

Result after the 29th (the last) move:

████████████████████████████████████████████████████████████████████████████████
██▓▓            ▓▓  ▓▓▓▓    ▓▓    ▓▓  ▓▓▓▓      ▓▓  ▓▓▓▓        ▓▓  ▓▓  ▓▓▓▓  ██
██▓▓▓▓  ▓▓                    ▓▓▓▓      ▓▓      ▓▓  ▓▓▓▓                  ▓▓  ██
██▓▓██  ▓▓▓▓      ▓▓▓▓▓▓▓▓            ▓▓    ▓▓▓▓▓▓▓▓    ▓▓        ▓▓▓▓▓▓    ▓▓██
██  ▓▓      ▓▓        ▓▓      ▓▓  ▓▓▓▓  ██▓▓▓▓              ▓▓                ██
██▓▓▓▓    ▓▓▓▓▓▓        ▓▓▓▓  ▓▓            ▓▓  ▓▓▓▓  ▓▓    ▓▓    ▓▓    ▓▓    ██
██                  ▓▓        ▓▓▓▓▓▓▓▓▓▓                        ▓▓    ██▓▓    ██
██            ▓▓▓▓  ██▓▓  ▓▓  ▓▓  ▓▓            ▓▓  ▓▓▓▓    ▓▓    ▓▓  ▓▓▓▓    ██
██              ▓▓  ▓▓  ▓▓▓▓◄►    ▓▓▓▓  ▓▓  ██                ▓▓▓▓      ▓▓    ██
██  ▓▓▓▓                  ▓▓▓▓▓▓▓▓▓▓    ▓▓▓▓      ▓▓▓▓▓▓▓▓            ▓▓    ▓▓██
██▓▓    ▓▓        ▓▓▓▓▓▓    ▓▓      ▓▓                ▓▓      ▓▓  ▓▓▓▓    ▓▓▓▓██
██          ▓▓            ██  ▓▓  ▓▓▓▓    ▓▓▓▓▓▓      ▓▓  ▓▓  ▓▓  ██        ▓▓██
██▓▓  ▓▓  ▓▓▓▓    ▓▓    ▓▓                  ▓▓▓▓    ▓▓▓▓  ▓▓  ▓▓  ▓▓▓▓▓▓      ██
██              ▓▓      ▓▓      ▓▓      ▓▓    ▓▓          ▓▓▓▓▓▓  ▓▓          ██
██  ▓▓▓▓    ▓▓    ▓▓  ▓▓▓▓      ▓▓              ▓▓  ▓▓  ▓▓          ▓▓        ██
██            ▓▓▓▓      ▓▓      ▓▓    ▓▓                  ▓▓            ▓▓▓▓  ██
██▓▓  ▓▓          ██        ▓▓▓▓▓▓▓▓    ▓▓        ▓▓▓▓▓▓        ██  ▓▓        ██
██    ▓▓      ▓▓  ▓▓      ▓▓                ▓▓                    ▓▓▓▓    ▓▓  ██
██    ▓▓      ▓▓          ██▓▓    ▓▓      ▓▓▓▓    ▓▓    ▓▓                  ▓▓██
██  ▓▓▓▓  ▓▓  ▓▓    ▓▓▓▓                                ▓▓      ▓▓            ██
██        ▓▓▓▓▓▓                ▓▓  ▓▓▓▓    ▓▓    ▓▓    ▓▓      ▓▓            ██
██  ▓▓  ▓▓          ▓▓                        ▓▓▓▓      ▓▓      ▓▓    ▓▓      ██
████████████████████████████████████████████████████████████████████████████████