????????
      +---------
HUECU | UUXXUPMP
       -HUECU
        =====
        HTHGTP
       - WPGRJ
        ======
         HHPXGM
        -HHREWW
         ======
           ETJPP
          -JHTCW
           =====
           ?????

base: 12
letters: CEGHJMPRTUWX
difficulty: medium