????????
      ----------
GPYMQ ) UWPRYRRM
       -UYGQQ
        =====
         UTRYR
        -YFRYQ
         =====
         GPQQRR
        -GGWTYQ
         ======
          GQRPRM
         -GQPFMQ
          ======
           ?????

base: 12
symbols: FGMNPQRTUWXY
missing: N X
difficulty: hard
hints: X << N