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.

输入描述:

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

输出描述:

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.