UGNV
      +---------
ZNQLW | HVHHWVXN
       -ZNQLW
        =====
        WLMXTV
       -WXTJXZ
        ======
         ZMWJYX
        -WLNGHY
         ======
          WQPRWN
         -WQWTGU
          ======
            JLYG

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard