????????
      ----------
ZPQXN ) YPNRQZPM
       -ZPQXN
        =====
        WHTHRZ
       - UYRVT
        ======
         GWLTNP
        -WNHNZP
         ======
          PYNRHM
         -PYTWTG
          ======
          ??????

base: 16
symbols: GHJLMNPQRTUVWXYZ
difficulty: medium
hints: N << M
missing: J