There are 13 trees on one side of a road, and the distance between two adjacent trees is 5 meters. Install a street lamp every 6 meters on the other side of the road, how many lamps need to be installed (from the beginning to the end).
一条路的一侧有13棵树，相邻两棵之间相距5米．在路的另一侧每隔6米安装一盏路灯，需要装多少盏灯(从头到尾)．
<gadget id="calculator">13 - 1</gadget>
<output>12</output>

<gadget id="calculator">5 * 12</gadget>
<output>60</output>

<gadget id="calculator">60 / 6</gadget>
<output>10</output>

<gadget id="calculator">10 + 1</gadget>
<output>11</output>

<result>11</result>