????????
      +---------
LGPPU | JLRJYTWU
       -QXWWX
        =====
        WHMQGT
       -WHYFHP
        ======
          XYUWW
         -TYTXJ
          =====
          YNWGPU
         - UHFGH
          ======
          ??????

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: hard