From A to B, originally installed a telegraph pole every 45 meters, plus 53 poles at both ends, now it is changed to install a telegraph pole every 60 meters, except that the two ends do not move, How many do not need to be moved in the middle?
从甲地到乙地，原来每隔45米装一根电线杆，加上两端的两根有53根，现改成每隔60米装一根电线杆，除两端两根不移动外，中间还有几根不必移动？
<gadget id="calculator">53 - 1</gadget>
<output>52</output>

<gadget id="calculator">45 * 52</gadget>
<output>2_340</output>

<gadget id="calculator">2_340 / 180</gadget>
<output>13</output>

<gadget id="calculator">13 - 1</gadget>
<output>12</output>

<result>12</result>