import java.util.Scanner;

public class PrimeTest1
{
/*******************************************************************************/
/**
 * This is a particularly mindless version of a prime-testing program that will
 * test whether an input integer 'n' is prime or not by trial dividing by all
 * integers less than or equal to the square root of the integer.
 *
 * There is nothing to commend this program to anyone except as an
 * example of a program that has a simple loop and a simple test.  
 * Subsequent versions of this program will do things in a more classy way.
 *
 * Details (written here so as not to clutter up the code):
 *   We import the Scanner class at the top and use it for console input.
 *
 *   Mathematically, we know there must be a divisor lessequal the square root.
 *
 *   We use the built in function Math.sqrt() to take the square root.
 *   This also requires casting 'n' to a double for the sqrt method and
 *   then casting the result back to an integer.
 *
 *   In this program we end from inside the loop.  This is bad form and in
 *   the next version we will end more smoothly.
 *
 * @author Duncan Buell
 * 3 February 2008
**/
  public static void main(String[] args)
  {
    int divisor,n,root;
    Scanner console = new Scanner(System.in);

// The nextInt method of Scanner takes the next integer input from the console
    n = console.nextInt();
    System.out.println("Test " + n + " for primality");

    divisor = 2;
    root = (int) Math.sqrt((double) n);
    System.out.println("Test for divisors up to " + root);
    while(divisor <= root)
    {
//    print from inside the loop to make sure that the program is executing as expected
      System.out.println("Test " + divisor + " as a possible divisor ");
      if(0 == (n % divisor))
      {
        System.out.println("The number  " + n + " is divisible by " + divisor + " and thus is not prime");
        System.out.println("Program terminating normally");
        System.exit(0);
      }
      divisor = divisor + 1;
    } // while(divisor <= root)

// If we run through all possible divisors and don't find one that divides, then the number must be prime.
    System.out.println("The number  " + n + " is prime");
    System.out.println("Program terminating normally");
  }
} // public class PrimeTest1