Fill in numbers in the three boxes of the six-digit number 3□2□1□ so that the number can be divisible by 15. What is the smallest of such six-digit numbers?
在六位数3□2□1□的三个方框里分别填入数字，使得该数能被15整除，这样的六位数中最小的是多少．
<result>302_010</result>