19 pieces can be placed on each side of the outermost layer of the Go board, how many pieces can be placed in total on the outermost layer.
围棋盘最外层每边能摆放19个棋子，最外层一共可以摆放多少个棋子．
<gadget id="calculator">19 * 4</gadget>
<output>76</output>

<gadget id="calculator">76 - 4</gadget>
<output>72</output>

<result>72</result>