????????
      +---------
PCCAG | CCGPRNJC
       -RCJPX
        =====
        ACJNUN
       -AUCGGH
        ======
         PJPJGJ
        -PUCXHH
         ======
          XHGXHC
         -XPCHCG
          ======
          ??????

base: 10
letters: ACGHJNPRUX
difficulty: medium