????????
      +---------
YYTGY | UGFNGNPX
       -XCRRX
        =====
         UYXRN
        -XCRRX
         =====
          XUPPP
         -NUYCN
          =====
          YFRNCX
         -YFUXRP
          ======
          ??????

base: 10
letters: CFGNPRTUXY
difficulty: medium