FYU
      +--------
GUQNQ | MXQYFWU
       -GUQNQ
        =====
        XYEFXW
       -XNUWQG
        ======
         FMCGUU
        -FUUHGN
         ======
           HUFH

base: 12
letters: CEFGHMNQUWXY
difficulty: medium