P24424 [AtCoder] At Most 2 Colors
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题目描述

Problem Statement

There is a grid with $1 \times N squares, numbered 1,2,\dots,N$ from left to right.
Takahashi prepared paints of C colors and painted each square in one of the C colors.
Then, there were at most two colors in any consecutive K squares.
Formally, for every integer i such that $1 \le i \le N-K+1,$ there were at most two colors in squares $i,i+1,\dots,i+K-1$.
In how many ways could Takahashi paint the squares?
Since this number can be enormous, find it modulo 998244353.

Input

The input is given from Standard Input in the following format:
N K C

Output

Print the answer as an integer.

Constraints

  • All values in the input are integers.
  • $2 \le K \le N \le 10^6$
  • $1 \le C \le 10^9$

Sample Input 1

3 3 3

Sample Output 1

21

In this input, we have $a 1 \times 3$ grid.
Among the 27 ways to paint the squares, there are 6 ways to paint all squares in different colors, and the remaining 21 ways are such that there are at most two colors in any consecutive three squares.

Sample Input 2

10 5 2

Sample Output 2

1024

Since C=2, no matter how the squares are painted, there are at most two colors in any consecutive K squares.

Sample Input 3

998 244 353

Sample Output 3

952364159

Print the number modulo 998244353.

输入格式

见题面 Input 部分

输出格式

见题面 Output 部分

样例输入
3 3 3
样例输出
21