YEF
      +---------
CPUYE | FMRNMUFP
       -HRXRNF
        ======
         REHHEF
        -RXFUPY
         ======
          UPMEPP
         -UENYFR
          ======
            FRXR

base: 11
letters: CEFHMNPRUXY
difficulty: intermediate
restrictions: no multiplication