A square pond has 15 trees on each side, one tree at each of the four vertices, and the distance between two adjacent trees is 4 meters. What is the perimeter of the square pond in meters?
一个正方形池塘，每边有15棵树，四个顶点都有1棵树，相邻两棵之间相距4米，这个正方形池塘的周长是多少米？
<gadget id="calculator">15 - 1</gadget>
<output>14</output>

<gadget id="calculator">4 * 14</gadget>
<output>56</output>

<gadget id="calculator">56 * 4</gadget>
<output>224</output>

<result>224</result>