????????
      +---------
NULNN | UUYFFPEX
       -NULNN
        =====
        NHHWUP
       -YGRGPL
        ======
         EYGLYE
        -EYYULF
         ======
           TTHXX
          -NULNN
           =====
           ?????

base: 13
letters: EFGHLNPRTUWXY
difficulty: medium