/**
 * ex 5.31
 * 
 * @author (CIS260) 
 * @version (2010.10.21)
 */
import java.util.Scanner;

public class CCvalidate
{
   

    public static void main(String args[])
    {
        // put your code here
        Scanner input = new Scanner(System.in);
        
        System.out.print("Enter a Credit Card Number: ");
        long usernumber = input.nextLong();
        
        if (isValid(usernumber) )
                System.out.println( usernumber + " is VALID");
        else
                System.out.println( usernumber + " is NOT VALID");
    }

    public static boolean isValid(long Number)
    {
        int ccsize = getSize( Number );
        if (ccsize < 13 || ccsize > 16 )
            return false;
            
        return true;
    }
    
    public static int sumOfDoubleEvenPlace(long number)
    { return 0; }
    
    public static int getDigit(int number)
    { return number; }
    
    public static int SunOfOddPlace(long number)
    { return 0; }
    
    public static boolean prefixMatched(long number, int d)
    { return true; }
    
    public static int getSize(long d)
    { 
        int numdigits = 0;
        
        while (d > 0)
        {
            d = d / 10;
            numdigits++;
        }
        
        return numdigits; }
    
    public static long getPrefix(long number, int k)
    { return 4; }
    
   
}