????????
      +---------
FJRJN | QRHTRGRX
       -FJRJN
        =====
        UULGMG
       - XFYQW
        ======
         WFMGFR
        -WWMHTU
         ======
          UPFQGX
         - XFYQW
          ======
          ??????

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: medium