?????????
      +----------
WTRQJ | PMNTUWURU
       -WTRQJ
        =====
         ULWRW
        -NJRWU
         =====
          TTWJU
         -QRMGW
          =====
          WMMMNR
         -WLUTFQ
          ======
           WQUMMU
          -WUJJNN
           ======
           ??????

base: 12
letters: FGJLMNPQRTUW
difficulty: intermediate