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*.
line = list(map(int,input().split()))
n = line[0]
m = line[1]

s = input()
a = [0]*(n+2)

k = 0
for i in range(n):
    a[i+1] = ord(s[i]) - ord('a') + 1
    if a[i+1] != a[i]:
        k+=1

sol = k*(m*n - n)

alt = 1
rest = 0
for i in range(2,n+1):
    if a[i] == a[i-2]:
        alt += 1
        continue
    if a[i] != a[i-1]:
        rest += (alt*(alt-1))//2
        alt = 2
        continue
    rest += (alt*(alt-1))//2
    alt = 1

print(sol - rest - (alt*(alt-1)//2))        
