第 45 届国际大学生程序设计竞赛（ICPC）亚洲区域赛（济南）C-Stone Game

题目

题目描述
MianKing has nn piles of stones and each pile has at most 3 stones, now he wants to merge all of these stones into one pile.

In order to achieve his goal, each time MianKing can choose two piles of stones and merge them into a new pile, and the number of stones in the new pile is the sum of these two piles.

Because it takes manpower to move stones, in each operation if the numbers of these two piles of stones are xx and yy respectively, MianKing should pay$(xmod3)(ymod3)$coins for it.

Now MianKing wants to know the minimum amount of coins he need to pay to merge all of these stones into one pile.

题意

这题题意比较绕，一上来还读错了。。
给你a1a_1