????????
      +---------
PUMTL | QTWFWRXR
       -PUMTL
        =====
        LHHYLR
       -LPQUXF
        ======
         PLMQHX
        -WYUMNY
         ======
          WWTRQR
         -WNRPYM
          ======
          ??????

base: 13
letters: FHLMNPQRTUWXY
difficulty: hard