백준 8단계 no.5

import java.util.*;

public class Main {
    static boolean prime(int m) {
        if (m != 1) {
            for (int j = 2; j <= Math.sqrt(m); j++) {
                if (m % j == 0) {
                    return false;
                }
            }
            return true;
        }
        return false;
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        Map<Integer, Integer> map = new LinkedHashMap<>();

        while (true) {
            int m = sc.nextInt();

            if (m == 0 ){
                break;
            }
            int count = 0;
            int end = m * 2;

            for (int i = m + 1; i <= end; i++) {
                if (prime(i)) {
                    count++;
                }
            }
            map.put(m, count);
        }

        map.forEach((key, value) -> {
            System.out.println(value);
        });
    }
}