public class RatRep2 implements RatRepIF {

    protected int num, den;
    //@ invariant den != 0 && gcd(num, den) == 1;

    public RatRep2(int given_n, int given_d)
    //@ requires given_d != 0;
    {
        int d = gcd(given_n, given_d);
        num = given_n / d;
        den = given_d / d;
    }

    public int numer() { return num; }
    public int denom() { return den; }

    protected int gcd(int a, int b) {
        while (b != 0) {
            int r = a % b;
            a = b;
            b = r;
        }
        return a;
    }

}