You are given a string S of length n with each character being one of the first m lowercase English letters. Calculate how many different strings T of length n composed from the first m lowercase English letters exist such that the length of LCS (longest common subsequence) between S and T is n - 1. Recall that LCS of two strings S and T is the longest string C such that C both in S and T as a subsequence.

输入描述:

The first line contains two numbers n and m denoting the length of string S and number of first English lowercase characters forming the character set for strings (1 ≤ n ≤ 100 000, 2 ≤ m ≤ 26).The second line contains string S.

输出描述:

Print the only line containing the answer.

备注:

For the first sample, the 6 possible strings T are: aab, aac, aba, aca, baa, caa. For the second sample, the 11 possible strings T are: aaa, aac, aba, abb, abc, aca, acb, baa, bab, caa, cab.For the third sample, the only possible string T is b.