There are three ropes, each with a length of 12 meters, 16 meters and 20 meters. They must be cut into small sections of the same length, and no surplus is allowed. What is the longest section?
有三根绳子，每根长12米、16米和20米，要把它们截成同样长的小段，不允许有剩余，每段最长是多少？
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<result>4</result>