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Language:
Primes
 Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 4995 Accepted: 1872

Description

A pretty straight forward task, calculate the number of primes between 2 integers.

Given 2 integers A ≤ B < 105 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.

Input

As many as 1000 lines, each line contains 2 integers A and B separated by a space. Input is terminated when A = B = -1 (Do not process this line).

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.

Sample Input

```0 9999
1 5
-1 -1```

Sample Output

```1229
3```

Source

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