write a go solution for Description:
Consider the following problem.

You are given a string s, consisting of n lowercase Latin letters, and an integer k (n is not divisible by k). Each letter is one of the first c letters of the alphabet.

You apply the following operation until the length of the string is less than k: choose a contiguous substring of the string of length exactly k, remove it from the string and glue the resulting parts together without changing the order.

Let the resulting string of length smaller than k be t. What is lexicographically smallest string t that can obtained?

You are asked the inverse of this problem. Given two integers n and k (n is not divisible by k) and a string t, consisting of (nbmodk) lowercase Latin letters, count the number of strings s that produce t as the lexicographically smallest solution.

Print that number modulo 998,244,353.

Input Format:
The first line contains three integers n,k and c (1<=n<=10^6; 2<=k<=10^6; 1<=c<=26; n is not divisible by k) — the length of string s, the length of the substring that is being removed and the number of first letters from the alphabet.

The second line contains string t, consisting of exactly (nbmodk) lowercase Latin letters. Each letter is one of the first c letters of the alphabet.

Output Format:
Print a single integer — the number of strings s that produce t as the lexicographically smallest solution.

Note:
The strings s in the first example: "aaa", "aab", "aba", "abb", "baa", "bba".

The strings s in the second example: "bcabc", "bcacc", "bcbbc", "bcbcc", "bccbc", "bcccc", "caabc", "cabbc", "cacbc", "cbabc", "cbbbc", "cbcbc", "ccabc", "ccbbc", "cccbc".. Output only the code with no comments, explanation, or additional text.