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.
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*.
n,m=map(int,input().split())
s=input()
v=0
c=s[0]
j=1
t=[]
front=0
p='#'
for i in range(1,len(s)):
	x=s[i]
	if c==x:
		j+=1
	else:
		if p==x and j==1:
			v-=1
		else:p=c
		c=x
		t+=[j]
		j=1
		front+=1
t+=[j]
v+=len(t)*((n-1)*m+(m-1)-(n-1))
v-=front
coll=n-1-front
print(v)