????????
      +---------
FLAMF | RULPMFUM
       -FLAMF
        =====
        FRYFYF
       -FRFLFL
        ======
          QQQQU
         -FLAMF
          =====
          PCURPM
         -PQAQCA
          ======
          ??????

base: 10
letters: ACFLMPQRUY
difficulty: hard