PPMU
      +---------
RHJPY | GEWYUWYM
       -GXWXE
        =====
         EXYYW
        -GXWXE
         =====
         RXRWQY
        - LXGRR
         ======
          RXMJWM
         -RXWRGP
          ======
            EGMP

base: 13
letters: EGHJLMPQRUWXY
difficulty: medium