public class Exercise4c
{
  public static class Truncated extends Exception { }

  // subtracts from a (an array of natural numbers) the corresponding 
  // elements of b (also an array of natural numbers) 
  // throws Truncated exception, if by the subtraction
  // some element of a would become negative
  public static void subtract(int[] a, int[] b) throws Truncated
  {
    int n = a.length;
    for (int i=0; i<n; i++)
    {
      if (a[i] < b[i]) throw new Truncated();
      a[i] = a[i]-b[i];
    }
  }
}