Orig Description
Prime-Factor Prime
A positive integer is called a "prime-factor prime" when the number of its prime factors is prime. For example, $12$ is a prime-factor prime because the number of prime factors of $12 = 2 \times 2 \times 3$ is $3$, which is prime. On the other hand, $210$ is not a prime-factor prime because the number of prime factors of $210 = 2 \times 3 \times 5 \times 7$ is $4$, which is a composite number.
In this problem, you are given an integer interval $[l, r]$. Your task is to write a program which counts the number of prime-factor prime numbers in the interval, i.e. the number of prime-factor prime numbers between $l$ and $r$, inclusive.
Input
The input consists of a single test case formatted as follows.
$l$ $r$
A line contains two integers $l$ and $r$ ($1 \leq l \leq r \leq 10^9$), which presents an integer interval $[l, r]$. You can assume that $0 \leq r-l < 1,000,000$.
Output
Print the number of prime-factor prime numbers in $[l,r]$.
Sample Input 1
1 9
Output for Sample Input 1
4
Sample Input 2
10 20
Output for Sample Input 2
6
Sample Input 3
575 57577
Output for Sample Input 3
36172
Sample Input 4
180 180
Output for Sample Input 4
1
Sample Input 5
9900001 10000000
Output for Sample Input 5
60997
Sample Input 6
999000001 1000000000
Output for Sample Input 6
592955
In the first example, there are 4 prime-factor primes in $[l,r]$: $4,6,8,$ and $9$.
Extracted Specification
An integer l (1 ≤ l ≤ 10^9).
An integer r (l ≤ r ≤ 10^9, and 0 ≤ r-l < 1,000,000).
### Example Input:
```
1 9
```
### Function Signature:
Write a function f(l, r) that takes in the input.
def f(l: int, r: int):
'''
l: an integer
r: an integer
'''
Test Case Generator
Sure, here is a test case generator for the "Prime-Factor Prime" problem:
```python
import random
def tcgen():
# Generate l and r such that 1 ≤ l ≤ r ≤ 10^9 and 0 ≤ r - l < 1,000,000
l = random.randint(1, 10**9 - 1_000_000)
r = l + random.randint(0, 999_999)
return l, r
# Example of generating a test case
l, r = tcgen()
print(f"{l} {r}")
```
This code snippet generates random valid test cases for the given problem. Specifically:
1. It ensures that `l` is between 1 and \(10^9 - 1,000,000\) to maintain a valid range.
2. It ensures that `0 ≤ r - l < 1,000,000` by adding a random value between 0 and 999,999 to `l` to get `r`.
To use the generated test case in your solution, you just need to call the `tcgen` function, which will produce a pair of integers, `l` and `r`, meeting the specified constraints.
Extract Arguments
def extract_arguments(fh):
l, r = map(int, fh.readline().strip().split())
return l, r