There are four numbers a, b, c, and d. It is known that the greatest common factor of a and b is 60, and the greatest common factor of c and d is 96. What is the greatest common factor of these four numbers?
有a、b、c、d四个数，已知a、b的最大公因数是60，c和d的最大公因数是96，这四个数的最大公因数是多少？
<gadget id="calculator">2 * 3 * 5</gadget>
<output>30</output>

<result>30</result>