Count the Primes

Problem Description

Xiaoming has just learned the concept of a prime: a prime is a positive integer greater than $1$ that cannot be divided evenly by any positive integer other than $1$ and itself. Now Xiaoming wants to find out how many primes there are between two positive integers $A$ and $B$ (including $A$ and $B$).

Input Format

A single line containing two positive integers $A, B$. It is guaranteed that $2 \le A \le B \le 1000$.

Output Format

Output one line containing an integer $C$, the number of primes found.

Sample Input

Sample Input 1

2 10

Sample Input 2

98 100

Sample Output

Sample Output 1

4

Sample Output 2

0

Sample Explanation

In the first sample, the input is $2$ and $10$, meaning we must find all primes from $2$ to $10$ inclusive. These primes are $2$, $3$, $5$, $7$, four in total, so the output is $4$.

Constraints

$2 \le A \le B \le 1000$