Prime-Factor Prime

A positive integer $n$ is a prime-factor prime when the number of its prime factors, counted with multiplicity, is itself prime. For example, 12 is a prime-factor prime: $12 = 2 \times 2 \times 3$ has 3 prime factors and 3 is prime. 210 is not a prime-factor prime, because $210 = 2 \times 3 \times 5 \times 7$ has 4 prime factors and 4 is composite.

You are given an integer interval $[l, r]$. Write a program that counts the prime-factor primes in that interval, that is, the prime-factor primes $n$ with $l \le n \le r$.

The input consists of a single test case in the following format.

l r

One line contains two integers $l$ and $r$ ($1 \le l \le r \le 10^9$, $0 \le r - l < 10^6$) describing the integer interval $[l, r]$.

Print the number of prime-factor primes in $[l, r]$.

In the first example the prime-factor primes in $[1, 9]$ are 4, 6, 8 and 9, so the answer is 4.