JJT
      +--------
ERJRW | ETUJYQJ
       -ERJRW
        =====
         FFULQ
        -ERJRW
         =====
         EJWRPJ
        -PTYPUH
         ======
          EEPFP

base: 13
letters: EFHJLMPQRTUWY
difficulty: hard
missing: M