LCS Again

2000ms

262144K

Description:

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.

Input:

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.

Output:

Print the only line containing the answer.

Sample Input:

3 3
aaa

Sample Output:

Sample Input:

3 3
aab

Sample Output:

Sample Input:

1 2
a

Sample Output:

Sample Input:

10 9
abacadefgh

Sample Output:

Note:

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.

Informação

Provedor Codeforces

Código CF578D