write a go solution for Description:
Consider a deck of cards. Each card has one of 4 suits, and there are exactly n cards for each suit — so, the total number of cards in the deck is 4n. The deck is shuffled randomly so that each of (4n)! possible orders of cards in the deck has the same probability of being the result of shuffling. Let c_i be the i-th card of the deck (from top to bottom).

Monocarp starts drawing the cards from the deck one by one. Before drawing a card, he tries to guess its suit. Monocarp remembers the suits of the k last cards, and his guess is the suit that appeared the least often among the last k cards he has drawn. So, while drawing the i-th card, Monocarp guesses that its suit is the suit that appears the minimum number of times among the cards c_i-k,c_i-k+1,...,c_i-1 (if i<=k, Monocarp considers all previously drawn cards, that is, the cards c_1,c_2,...,c_i-1). If there are multiple suits that appeared the minimum number of times among the previous cards Monocarp remembers, he chooses a random suit out of those for his guess (all suits that appeared the minimum number of times have the same probability of being chosen).

After making a guess, Monocarp draws a card and compares its suit to his guess. If they match, then his guess was correct; otherwise it was incorrect.

Your task is to calculate the expected number of correct guesses Monocarp makes after drawing all 4n cards from the deck.

Input Format:
The first (and only) line contains two integers n (1<=n<=500) and k (1<=k<=4*n).

Output Format:
Let the expected value you have to calculate be an irreducible fraction dfracxy. Print one integer — the value of x*y^-1bmod998244353, where y^-1 is the inverse to y (i. e. an integer such that y*y^-1bmod998244353=1).

Note:
None. Output only the code with no comments, explanation, or additional text.