P8707 [AtCoder] AtCoder Grand Contest 021 - Trinity
NOI
题目描述

We have an $N \times M$ grid. The square at the i-th row and j-th column will be denoted as (i,j). Particularly, the top-left square will be denoted as (1,1), and the bottom-right square will be denoted as (N,M). Takahashi painted some of the squares (possibly zero) black, and painted the other squares white.

We will define an integer sequence A of length N, and two integer sequences B and C of length M each, as follows:

  • $A_i(1\leq i\leq N)$ is the minimum j such that (i,j) is painted black, or M+1 if it does not exist.
  • $B_i(1\leq i\leq M)$ is the minimum k such that (k,i) is painted black, or N+1 if it does not exist.
  • $C_i(1\leq i\leq M)$ is the maximum k such that (k,i) is painted black, or 0 if it does not exist.

How many triples (A,B,C) can occur? Find the count modulo 998244353.

Constraints

  • $1 \leq N \leq 8000$
  • $1 \leq M \leq 200$
  • N and M are integers.

Partial Score

  • 1500 points will be awarded for passing the test set satisfying $N\leq 300$.

Constraints

  • $1 \leq N \leq 8000$
  • $1 \leq M \leq 200$
  • N and M are integers.

Input

Input is given from Standard Input in the following format:

N M

Output

Print the number of triples (A,B,C), modulo 998244353.

Examples

Input

2 3

Output

64

Input

4 3

Output

2588

Input

17 13

Output

229876268

Input

5000 100

Output

57613837

输入格式

见题面

输出格式

见题面

样例输入
5000 100
样例输出
57613837