/**********************************************************************
 * Matt Kretchmar
 * March 21, 2003
 * PrimeTest
 * This program will test the user's input integer to see if it 
 * is a prime number or not.
 **********************************************************************/
import java.util.Scanner;

class PrimeTest
{
  /********************************************************************
   * main
   ********************************************************************/
  public static void main ( String [] args )
  {
    int n, x, y;
    Scanner keyboard = new Scanner(System.in);
    
    System.out.println("Enter x: ");
    x = keyboard.nextInt();
    System.out.println("Is x prime? " + isPrime(x) );
  }
  /********************************************************************
   * evenlyGoesInto
   * This method returns true if y divides x evenly (with no remainder)
   * or returns false otherwise.
   ********************************************************************/
  public static boolean evenlyGoesInto ( int x, int y )
  {
    return ( x%y == 0 );
  }
  /********************************************************************
   * isPrime
   * This method returns true if x is prime, false otherwise.  It works
   * by testing all numbers 2, 3, ... up through sqrt(x) to see if any
   * of them are factors (divide evenly) of x.  If no factors are found,
   * then x is a prime number.
   ********************************************************************/
  public static boolean isPrime ( int x )
  {
    for ( int i = 2; i <= Math.sqrt(x); i++ )
    {
      if (evenlyGoesInto(x,i)) 
        return false;
    }
    return true;
  }
}