????????
      +---------
PPFTU | YUFLMXHW
       -PPFTU
        =====
        TWNPFX
       - PPFTU
        ======
         RXHQLH
        -RTMHQF
         ======
          TPMRXW
         -TMWWQR
          ======
          ??????

base: 14
letters: FGHLMNPQRTUWXY
difficulty: hard
missing: G