Appleman has n cards. Each card has an uppercase letter written on it. Toastman must choose k cards from Appleman's cards. Then Appleman should give Toastman some coins depending on the chosen cards. Formally, for each Toastman's card i you should calculate how much Toastman's cards have the letter equal to letter on ith, then sum up all these quantities, such a number of coins Appleman should give to Toastman.

Given the description of Appleman's cards. What is the maximum number of coins Toastman can get?

The first line contains two integers n and k (1 ≤ k ≤ n ≤ 10⁵). The next line contains n uppercase letters without spaces — the i-th letter describes the i-th card of the Appleman.

Print a single integer – the answer to the problem.