????????
      +---------
GJMFL | YHLXQUXX
       -GJMFL
        =====
        FFFLJU
       - EHJMY
        ======
         FHQWRX
        -FHFUFW
         ======
           YGYYX
          -GJMFL
           =====
           ?????

base: 13
letters: EFGHJLMQRUWXY
difficulty: intermediate