????????
      +---------
LGTFQ | URFQJFUG
       -LGTFQ
        =====
        JLJXYF
       -JRQRGT
        ======
         JFRQJU
        - LGTFQ
         ======
          RLTLTG
         -RFLYFJ
          ======
          ??????

base: 11
letters: FGJLMQRTUXY
missing: M
difficulty: medium