소수판별 2 (Check Prime Number 2)

Main.java

import java.util.Scanner;

/**
 * 소수판별 2 (Check Prime Number 2)
 * 
 * @author devetue
 */
public class Main {
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		sc.close();

		int res = -1;
		int sqrtN = (int) Math.sqrt(N);

		for (int i = 2; i < sqrtN; i++) {
			if (N % i == 0) {
				res = i;
				break;
			}
		}

		if (res != -1 || N == 1) {
			System.out.println(N + " isn't prime number");
		}

		else {
			System.out.println(N + " is prime number ");
		}
	}
}