We are given two strings A and B which satisfy these conditions :
1.A and B both consist of exactly n characters each.
2.Each character in A and B is one of the first k lowercase letters of English alphabet.
3.There exists a string C such that A+C=C+B.
Note: + denotes string concatenation
For example, if n = 3 and k = 4 then one valid pair of strings is ("aad", "daa"): both strings have length 3, only the first 4 letters are used in each of them, and C = "aa" shows that the third condition is satisfied as well.
We are given n and k. Find the number of such pairs of strings and return the number modulo 1,000,000,007.
Constraints
n<= 1000,000,000
k<=26
six cases are ---("aa", "aa"), ("ab", "ab"), ("ab", "ba"), ("ba", "ab"), ("ba", "ba"), ("bb", "bb").