Time limit: 1.0s
Memory limit: 32M
The sieve of Eratosthenes is a famous algorithm to find all prime numbers up to . The algorithm is:
- Write down all integers between and , inclusive.
- Find the smallest number not already crossed out and call it ; is prime.
- Cross out and all its multiples that aren't already crossed out.
- If not all numbers have been crossed out, go to step .
Write a program that, given and , find the integer to be crossed out.
The integers and .
Output the number to be crossed out.
Sample Input 1
Sample Output 1
Sample Input 2
Sample Output 2
Sample Input 3
Sample Output 3
In the third example, we cross out, in order, the numbers and . The seventh number is .