In a chorus competition, 8 people with different heights should stand in two rows, with 4 people in each row, and align front to back. And everyone in the second row must be taller than the person in front of him, so as not to be blocked. How many different queuing methods are there?
在一次合唱比赛中，有身高互不相同的8个人要站成两排，每排4个人，且前后对齐．而且第二排的每个人都要比他身前的那个人高，这样才不会被挡住．一共有多少种不同的排队方法？
<gadget id="calculator">28 * 15 * 6 * 1</gadget>
<output>2_520</output>

<result>2_520</result>