Alex likes solving problems on WOJ (http://acm.whu.edu.cn/oak). As we all know, a beautiful balloon will appears when a
problem is solved. Alex loves balloons, especially when they're in a consecutive column, from which he can get a sense of
accomplishment.
Problems on WOJ have a variety of difficulties. Hard problems cost more time, while easy ones may be "killed in 1
second". Now we know that WOJ has N problems, numbered from 1 to N. Alex calls the solved problems in one
consecutive column as a "successful string". The length of a successful string is the number of problems it contains. Also
he defines the value of a successful string as the square of the string's length. Alex hopes to solve a certain number of
problems in M time, so he can get some successful strings, now he wants to maximize the sum of all the strings' value.