学生们决定去游乐园。他们中的一些人和父母在一起。总共有n个人来到公园，他们都想到达最极致的景点，并在上面滚动一次。
景点上出售x人组的门票，每组至少应有一名成年人（可能由一名成年人组成）。这类团体的票价是c1 + c2*(x - 1)^2（特别是，如果该组由一个人组成，则价格为c1）。
所有来到公园的学生和他们的父母决定分成小组，每个游客只加入一个小组，参观最极端的景点的总价格尽可能低。你要确定这个可能的最低总价。每组至少应有一名成年人。
Pupils decided to go to amusement park. Some of them were with parents. In total,
n people came to the park and they all want to get to the most extreme attraction and roll on it exactly
once.
Tickets for group of
x people are sold on the attraction, there should be at least one adult in each group (it is possible that the group consists of one adult). The ticket price for such group is
c1+c2·(x-1)2 (in particular, if the group consists of one person, then the price is
c1).
All pupils who came to the park and their parents decided to split into groups in such a way that each visitor join exactly one group, and the total price of visiting the most extreme attraction is as low as possible. You are to determine this minimum possible total price. There should be at least one adult in each group.
Output
Print the minimum price of visiting the most extreme attraction for all pupils and their parents. Each of them should roll on the attraction exactly once.
Note
In the first test one group of three people should go to the attraction. Then they have to pay
4+1*(3-1)2=8.
In the second test it is better to go to the attraction in two groups. The first group should consist of two adults (for example, the first and the second person), the second should consist of one pupil and one adult (the third and the fourth person). Then each group will have a size of two and for each the price of ticket is
7+2*(2-1)2=9. Thus, the total price for two groups is
18.