프로그램 명: coci_reseto
제한시간: 1 초
[문제요약] N 까지의 소수를 구할 때 이용하는 알고리즘 에라토스테네스의 체를 알고 있죠?
문제는 N 과 K 가 주어질 때 K 번째로 걸러지는(지워지는) 수를 구하는 것이 문제이다.
The sieve of Eratosthenes is a famous algorithm to find all prime numbers up to N. The algorithm is:
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Write down all integers between 2 and N, inclusive.
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Find the smallest number not already crossed out and call it P; P is prime.
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Cross out P and all its multiples that aren't already crossed out.
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If not all numbers have been crossed out, go to step 2.
Write a program that, given N and K, find the K-th integer to be crossed out.
입력
The integers N and K (2 ≤ K < N ≤ 1000).
출력
Output the K-th number to be crossed out.
입출력 예
input
7 3
output
6
input
15 7
output
12
input
10 7
output
9
EXAMPLES
In the third example, we cross out, in order, the numbers 2, 4, 6, 8, 10, 3, 9, 5 and 7. The seventh
number is 9.
출처: coci 2008/2009 2/6
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