# Double Happiness

## 题意翻译

**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

## 题目描述

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.

## 输入输出格式

### 输入格式

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

### 输出格式

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.

## 输入输出样例

### 输入样例 #1

``````3 5
``````

### 输出样例 #1

``````1
``````

### 输入样例 #2

``````6 66
``````

### 输出样例 #2

``````7
``````