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1194. Prime

单点时限: 2.0 sec

内存限制: 256 MB

A prime is the number which can be only divide exactly by or itself.

输入格式

There several test case. Each test case have two positive integer in one line.

输出格式

For each test case, output one line that contain an integer that is the number of primes from to .

样例

Input
5 10
1 3
6 8
Output
2
2
1
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