// File: Prime.java
// Written By: Deepak Kumar
// Date: Sep 29, 2020
// Purpose: Is an input n a prime number?
// Usage: java-introcs Prime n

public class Prime {
    public static void main(String[] args) {
        int n = Integer.parseInt(args[0]);

        if (n <= 1) {
            // Error message and quit
            System.out.println("Sorry, the number has to be >1. Try again.");
            System.exit(0);
        }

        // n > 1
        boolean isPrime = true;

        for (int i = 2; i <= n/2; i++) {
            // Does i divide n evenly?
            if (n % i == 0) {
                isPrime = false;
                break;
            }
        }

        // check is n is prime
        if (isPrime) {
            System.out.println("It is a prime number.");
        }
        else {
            System.out.println("It is not a prime number.");
        }
    } // main()
} // class Prime