题目来源:http://acm.hit.edu.cn/hoj/problem/view?id=2276

Count prime

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  Source : SCU Programming Contest 2006 Final
  Time limit : 1 sec   Memory limit : 64 M

Submitted : 741, Accepted : 177

Given an integer interval [L, R](L <= R <= 2147483647, R - L <= 1000000), please calculate the number of prime(s) in the interval.

Input

Multiple cases.
There is one line in each case, which contains two integer: L, R.

Output

There is only one line for each case, which contains the number of prime(s) in the interval.

Sample Input
2 11
Sample Output
5