1, 1, 3, 3, 7, 7, 9, 9 Take five numbers from them, at least 4 of which are different from each other, and the unit digit of the product of these five numbers is 1. What is the sum of these five numbers? How many?
1、1、3、3、7、7、9、9从中取五个数，其中至少4个数字互不相同，且这五个数的乘积个位为1，问这五个数的和是多少？
<gadget id="calculator">1 + 3 + 7 + 9 + 9</gadget>
<output>29</output>

<result>29</result>