There is a rectangular vegetable field with a length of 15 meters and a width of 7 meters. Now it is necessary to dig a ditch with a width of 1 meter around the outer edge of the vegetable field. What is the perimeter of the ditch in meters?
有一块长方形菜地，长15米，宽7米，现要在这块菜地的外沿周围挖一条宽1米的水沟，那么这条水沟的外沿周长是多少米？
<gadget id="calculator">15 + 1 + 1</gadget>
<output>17</output>

<gadget id="calculator">7 + 1 + 1</gadget>
<output>9</output>

<gadget id="calculator">17 + 9</gadget>
<output>26</output>

<gadget id="calculator">26 * 2</gadget>
<output>52</output>

<result>52</result>