?????????
      +----------
UTUXR | HUGMUGTLM
       -UTUXR
        =====
         WNTNG
        -QRRUH
         =====
         UWRFFT
        -UQQJLF
         ======
           NNQGL
          -NXWHX
           =====
            FJFLM
           -MQQUF
            =====
            ?????

base: 14
letters: FGHJLMNQRTUWXY
missing: Y
difficulty: medium