[백준] 4948 : 베르트랑 공준 -JAVA - 사좋배 공유

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		int[] arr =new int[200000];
		int i=0;
		int cnt=0;
		int count=0;
		Scanner sc = new Scanner(System.in);
		int number=1;
		while(number!=0) {
			number=sc.nextInt();
			arr[i]=number;
			i++;
		}
		
		for(int j=0;j<i-1;j++) {
			for(int k=arr[j]+1;k<=arr[j]*2;k++) {
				for(int z=1;z<Math.sqrt(k+1);z++) {
					if(k%z==0) {
						cnt++;
					}
					if(cnt>1) {
						break;
					}
				}
				if(cnt<2) {
					count++;
			}
				cnt=0;
		}
			System.out.println(count);
			count=0;
	}

		
		
	}

}