Put 52 ping-pong balls in 9 boxes, the number of ping-pong balls in each box is different, each box contains at least one ping-pong ball, then how many ping-pong balls are in the most box.
将52个乒乓球放在9个盒子里，每个盒子放的乒乓球个数都不相同，每个盒子至少放了一个乒乓球，那么最多的一个盒子放了多少个乒乓球．
<result>16</result>