YXW
      +--------
MUWEU | QEEGQUW
       -QMYTG
        =====
         RQMXU
        -WRWUQ
         =====
          EWPFW
         -RGMGR
          =====
           RJFG

base: 13
letters: EFGJMPQRTUWXY
difficulty: hard
missing: J