????????
      +---------
UCRPU | CCPGQRCA
       -UCRPU
        =====
        HTRGPR
       - UCRPU
        ======
         JACPUC
        -JGARPH
         ======
          JGRCUA
         -HAQPPR
          ======
          ??????

base: 10
letters: ACGHJPQRTU
difficulty: easy