The sum of three consecutive natural numbers is 60. What is the smallest of these three natural numbers?
三个连续自然数的和为60，这三个自然数中，最小的是多少．
<gadget id="calculator">60 / 3</gadget>
<output>20</output>

<gadget id="calculator">20 - 1</gadget>
<output>19</output>

<result>19</result>