import java.io.* ;
class DigitsLib
{
  public static boolean isZero (int [ ] digits)  
  {
   return digits[0] == 0; 
  }
  
  public static int [ ] readDigits( ) 
  { 
    int [ ] intArray;
  System.out.println("Please input the credit card number as four ");
  System.out.println("numbers of four digits, separated by spaces;");   
  System.out.println("or press 0 to finish."); 
  intArray = ITI1120.readIntLine( );
  return intArray;
  }
  
  public static int sumDigits (int x)  
  {
   int sum = 0;
   while (x != 0)
   {
     sum = sum + x % 10;
     x = x / 10;
   }
   return sum;

  }
}