Timber

2000ms

262144K

Description:

There is a beautiful alley with trees in front of a shopping mall. Unfortunately, it has to go to make space for the parking lot.

The trees on the alley all grow in a single line. There are $$$n$$$ spots for trees, index $$$0$$$ is the shopping mall, index $$$n+1$$$ is the road and indices from $$$1$$$ to $$$n$$$ are the spots for trees. Some of them are taken — there grow trees of the same height $$$k$$$. No more than one tree grows in each spot.

When you chop down a tree in the spot $$$x$$$, you can make it fall either left or right. If it falls to the left, it takes up spots from $$$x-k$$$ to $$$x$$$, inclusive. If it falls to the right, it takes up spots from $$$x$$$ to $$$x+k$$$, inclusive.

Let $$$m$$$ trees on the alley grow in some spots $$$x_1, x_2, \dots, x_m$$$. Let an alley be called unfortunate if all $$$m$$$ trees can be chopped down in such a way that:

no tree falls on the shopping mall or the road;
each spot is taken up by no more than one fallen tree.

Calculate the number of different unfortunate alleys with $$$m$$$ trees of height $$$k$$$. Two alleys are considered different if there is a spot $$$y$$$ such that a tree grows in $$$y$$$ on the first alley and doesn't grow in $$$y$$$ on the second alley.

Output the number modulo $$$998\,244\,353$$$.

Input:

The only line contains three integers $$$n, m$$$ and $$$k$$$ ($$$1 \le m, k \le n \le 3 \cdot 10^5$$$) — the number of spots for the trees, the number of trees and the height of each tree.

Output:

Print a single integer — the number of different unfortunate alleys with $$$m$$$ trees of height $$$k$$$, modulo $$$998\,244\,353$$$.

Sample Input:

6 1 4

Sample Output:

Sample Input:

5 2 2

Sample Output:

Sample Input:

6 2 2

Sample Output:

Sample Input:

15 3 2

Sample Output:

Informação

Provedor Codeforces

Código CF1821F