Problem:
Score : 600 points

Problem Statement

Find the number of sequences of length K consisting of positive integers such that the product of any two adjacent elements is at most N, modulo 10^9+7.

Constraints

1\leq N\leq 10^9

1 2\leq K\leq 100 (fixed at 21:33 JST)

N and K are integers.

Input

Input is given from Standard Input in the following format:

N K

Output

Print the number of sequences, modulo 10^9+7.

Sample Input 1

3 2

Sample Output 1

5

(1,1), (1,2), (1,3), (2,1), and (3,1) satisfy the condition.

Sample Input 2

10 3

Sample Output 2

147

Sample Input 3

314159265 35

Sample Output 3

457397712

Solution in Rust (1.15.1) (judge verdict: Runtime Error)

use std::io::{self, BufRead};
use std::mem::swap;

const M: i64 = 1000000007;

fn main() {
  let stdin = io::stdin();
  let mut lines = stdin.lock().lines();
  let xs: Vec<usize> = lines.next().unwrap().unwrap().split(' ').map(|x| x.parse().unwrap()).collect();
  let (n, k) = (xs[0], xs[1]);
  let mut count: Vec<i64> = (1..(n as i64 + 1)).collect();
  for _ in 0..(k-1) {
    let mut temp: Vec<i64> = vec![0; n];
    temp[0] = count[n-1];
    for i in 1..n {
      temp[i] = (temp[i-1] + count[(n/(i+1))-1]) % M;
    }
    swap(&mut count, &mut temp);
  }
  println!("{}", count[n-1]);
}