Double Happiness


**题目描述** 给定闭区间$ [l,r] $,找出区间内满足$ t=a^{2}+b^{2} $的所有素数$ t $的个数( $ a,b $为任意正整数). **输入格式** 输入只有一行 给定两个正整数$ l,r $表示区间范围 **输出格式** 输出一个数字 表示共有多少个素数t


On the math lesson a teacher asked each pupil to come up with his own lucky numbers. As a fan of number theory Peter chose prime numbers. Bob was more original. He said that number $ t $ is his lucky number, if it can be represented as: $ t=a^{2}+b^{2}, $ where $ a,b $ are arbitrary positive integers.Now, the boys decided to find out how many days of the interval $ [l,r] $ ( $ l<=r $ ) are suitable for pair programming. They decided that the day $ i $ ( $ l<=i<=r $ ) is suitable for pair programming if and only if the number $ i $ is lucky for Peter and lucky for Bob at the same time. Help the boys to find the number of such days.



The first line of the input contains integer numbers $ l,r $ ( $ 1<=l,r<=3·10^{8} $ ).


In the only line print the number of days on the segment $ [l,r] $ , which are lucky for Peter and Bob at the same time.


输入样例 #1

3 5

输出样例 #1


输入样例 #2

6 66

输出样例 #2