RHT
      +--------
QWRJU | XRJWQGP
       -JYTUP
        =====
        QGHTTG
       -QGUQRG
        ======
          FJRMP
         -UHFNG
          =====
          QJFRJ

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: hard
missing: L