/* Week 5 Discussion
 * PrimeTest.java
 * To check whether an integer is a prime.
 */

import java.util.*;

class PrimeTest {	

    public static void main(String args[]) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter a positive number: ");
        int num = scanner.nextInt();
        if (isPrime(num))
            System.out.println(num + " is a prime.");
        else
            System.out.println(num + " is not a prime.");
    }

    // Returns true if num is a prime, otherwise returns false.
    // Precond: num > 0
    public static boolean isPrime(int num) {
        boolean isPrime = false;
        if (num > 1) {
            isPrime = true;
            for (int i = (int) Math.sqrt(num); i > 1 && isPrime; i--) 
                if (num % i == 0) 
                    isPrime = false;
        }

        return isPrime;
    }

}