????????
      +---------
YPYNQ | UXNTYJTF
       -NQNYM
        =====
         MLLGJ
        -YPYNQ
         =====
         JWQJRT
        -WHYGPR
         ======
          JRYMHF
         -JYXJFJ
          ======
          ??????

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: hard