# Primes

Time Limit: 1000MS

Memory Limit: 65536K

## Description

A pretty straight forward task, calculate the number of primes between 2 integers.
Given 2 integers A ≤ B < 10^{5} what’s the number of primes in range from A to B inclusive.
Note: A prime number is a positive integer greater than 1 and is divisible by 1 and itself only. For N to be prime it is enough to test the divisibility of numbers less than or equal to square root of N.

## Output

For every line in input – except for the last line where A = B = -1 - print the number of prime numbers between A and B inclusive.

## Source

Seventh ACM Egyptian National Programming Con