CF113C.Double Happiness

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.

在数学课上，老师让每位学生提出自己心目中的幸运数字。作为数论爱好者，彼得选择了素数。鲍勃则更有创意，他称一个数 $t$ 是他的幸运数字，当且仅当它可以表示为：

$$t = a^2 + b^2,$$

其中 $a, b$ 是任意正整数。

现在，两个男孩决定找出区间 $[l, r]$（满足 $l \leq r$）中有多少天适合结对编程。他们约定：第 $i$ 天（满足 $l \leq i \leq r$）适合结对编程，当且仅当数字 $i$ 同时是彼得的幸运数字（即 $i$ 是素数）和鲍勃的幸运数字（即 $i$ 可表示为两个正整数的平方和）。请帮助这两个男孩求出满足条件的天数。

The first line of the input contains integer numbers l, r (1 ≤ l, r ≤ 3·108).

输入的第一行包含整数 $l$ 和 $r$（$1 ≤ l, r ≤ 3·10^8$）。

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.

在唯一的一行中输出区间 ([l, r]) 内同时对 Peter 和 Bob 都是幸运日的天数。