public class Poly {
   //OVERVIEW: Polys are immutable polynomials with integer coefficients.
  //A typical Poly is c0 + c1x + . . .
  // constructors
   public Poly ( )
      //EFFECTS: Initializes this to be the zero polynomial.

   public Poly (int c, int n) throws NegativeExponentException
      //EFFECTS: If n < 0 throws NegativeExponentException else
     //initializes this to be the Poly cxn.
     // methods
   public int degree ( )
      //EFFECTS: Returns the degree of this, i.e., the largest exponent
    //with a non-zero coefficient. Returns 0 if this is the zero Poly.

   public int coeff (int d)
      //EFFECTS: Returns the coefficient of the term of this whose exponent is d.

   public Poly add (Poly q) throws NullPointerException
      //EFFECTS: If q is null throws NullPointerException else
     //returns the Poly this + q.

   public Poly mul (Poly q) throws NullPointerException
      //EFFECTS: If q is null throws NullPointerException else
     //returns the Poly this * q.

   public Poly sub (Poly q) throws NullPointerException
      //EFFECTS: If q is null throws NullPointerException else
     //returns the Poly this - q.

   public Poly minus ( )
      //EFFECTS: Returns the Poly - this.
}