Four of the eight natural numbers from 1 to 8 are used to form a four-digit number, and the numbers from ones to thousands increase sequentially, and the difference between any two numbers is not 1. How many people are there in such a four-digit number?
用1至8这八个自然数中的四个组成四位数，从个位到千位的数字依次增大，且任意两个数字的差都不是1，这样的四位数共有多少人．
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<result>5</result>