Vasya and prime numbers#2065
Vasya learned in a math lesson that prime numbers are positive integers that are only divisible by and themselves, but for some reason, the number is not considered a prime. Vasya also learned that someone named Petya likes to give many problems called "from to ." So Vasya came up with a new task: count the number of prime numbers in the interval from to .
The input consists of several test cases. Each test case is on a separate line and contains two integers (possibly negative) and (l \leq r, |l|, |r| < 10^6). The last line contains two numbers and is not processed.
For each test case, print the number of prime numbers in the given interval on a separate line.
Example 1
Example 2