Modular Stability
Description
We define $x \bmod y$ as the remainder of division of $x$ by $y$ ($\%$ operator in C++ or Java, mod operator in Pascal).
Let's call an array of positive integers $[a_1, a_2, \dots, a_k]$ stable if for every permutation $p$ of integers from $1$ to $k$, and for every non-negative integer $x$, the following condition is met:
That is, for each non-negative integer $x$, the value of $(((x \bmod a_1) \bmod a_2) \dots \bmod a_{k - 1}) \bmod a_k$ does not change if we reorder the elements of the array $a$.
For two given integers $n$ and $k$, calculate the number of stable arrays $[a_1, a_2, \dots, a_k]$ such that $1 \le a_1 < a_2 < \dots < a_k \le n$.
The only line contains two integers $n$ and $k$ ($1 \le n, k \le 5 \cdot 10^5$).
Print one integer — the number of stable arrays $[a_1, a_2, \dots, a_k]$ such that $1 \le a_1 < a_2 < \dots < a_k \le n$. Since the answer may be large, print it modulo $998244353$.
Input
The only line contains two integers $n$ and $k$ ($1 \le n, k \le 5 \cdot 10^5$).
Output
Print one integer — the number of stable arrays $[a_1, a_2, \dots, a_k]$ such that $1 \le a_1 < a_2 < \dots < a_k \le n$. Since the answer may be large, print it modulo $998244353$.
Samples
7 3
16
3 7
0
1337 42
95147305
1 1
1
500000 1
500000