There are 13 boxes. Now put apples in them. It is required that each box contains an odd number of apples. No matter how these apples are placed, you can always find 4 boxes with the same number of apples. Question: How many are there at most? apple?
有13个箱子，现在往里面装苹果，要求每个箱子里装的苹果都是奇数个，无论这些苹果怎么放，总能找到4个箱子的苹果个数是一样的，问：最多有多少个苹果？
<gadget id="calculator">1 + 3 + 5 + 7</gadget>
<output>16</output>

<gadget id="calculator">16 * 3</gadget>
<output>48</output>

<gadget id="calculator">48 + 7</gadget>
<output>55</output>

<result>55</result>