????????
      +---------
PPEGM | XXYMWWXM
       -XMRMMF
        ======
         GWEYHX
        -GEHEFY
         ======
          XMYXMM
         -YWGEHW
          ======
          ??????

base: 11
letters: EFGHLMPRWXY
missing: L
difficulty: hard