????????
      +---------
URUHP | YMYHGYHU
       -URUHP
        =====
        WGMHWY
       -WPWRWM
        ======
         WHRHUH
        - URUHP
         ======
          MYCGTU
         -MLGCWU
          ======
          ??????

base: 12
letters: CGHLMPQRTUWY
missing: Q
difficulty: intermediate