P25095 [AtCoder] Multiple Sequences
普及+
题目描述

Problem Statement

Given are integers N and M.
How many sequences A of N integers satisfy the following conditions?

  • $1 \leq A_i \leq M \left(i = 1, 2, \ldots, N\right)$
  • A_{i+1} is a multiple of $A_i. \left(i = 1, 2, \ldots, N - 1\right)$

Since the answer can be enormous, report it modulo 998244353.

Input

Input is given from Standard Input in the following format:
N M

Output

Print the answer.

Constraints

  • All values in input are integers.
  • $1 \leq N \leq 2 \times 10^5$
  • $1 \leq M \leq 2 \times 10^5$

Sample Input 1

3 4

Sample Output 1

13

Some of the sequences A satisfying the conditions follow:

  • $A = \left(1, 1, 4\right)$
  • $A = \left(3, 3, 3\right)$
  • $A = \left(1, 2, 4\right)$

Sample Input 2

20 30

Sample Output 2

71166

Sample Input 3

200000 200000

Sample Output 3

835917264

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 4
样例输出
13