Calculating roots of quadratic equation using Java

class Quad{
        public static void main(String args[])
        {
                int a,b,c;
                double d,r1,r2;
                a=Integer.parseInt(args[0]);
                b=Integer.parseInt(args[1]);
                c=Integer.parseInt(args[2]);
                d=b*b-4*a*c;
                if(d==0)
                {
                        r1=-b+Math.sqrt(d)/(2*a);
                        System.out.println("Roots are real and equal:\nRoot="+r1);
                }
                else if(d>0)
                {
                        r1=-b+Math.sqrt(d)/(2*a);
                        r2=-b-Math.sqrt(d)/(2*a);
                        System.out.println("Roots are real and unequal:\nRoot 1="+r1+"\nRoot 2="+r2);
                }
                else
                        System.out.println("Roots are imaginary.");
        }
}