YRPQ
    +-------
YYN | PLQGHN
     -TPL
      ===
      XQWG
     -XRPT
      ====
       FRMH
      -FJPN
       ====
        FYXN
       -FFGU
        ====
          GN

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: hard