UWRX
      +---------
UPXGW | WWQNPWZM
       -UPXGW
        =====
         VJQZW
        -XZNPV
         =====
          QRMPZ
         -QUJLH
          =====
           GWTZM
          -TYYTN
           =====
           UGJGG

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: medium