Divide 15 apples into 4 piles with different numbers, how many apples are in the pile with the largest number.
把15个苹果分成数量都不相同的4堆，其中数量最多的一堆有多少个苹果．
<gadget id="calculator">15 - 1 - 2 - 3</gadget>
<output>9</output>

<result>9</result>