public class QuadraticRoots {
    private static class Complex {
        double re, im;

        public Complex(double re, double im) {
            this.re = re;
            this.im = im;
        }

        @Override
        public boolean equals(Object obj) {
            if (obj == this) {return true;}
            if (!(obj instanceof Complex)) {return false;}
            Complex other = (Complex) obj;
            return (re == other.re) && (im == other.im);
        }

        @Override
        public String toString() {
            if (im == 0.0) {return String.format("%g", re);}
            if (re == 0.0) {return String.format("%gi", im);}
            return String.format("%g%c%gi", re,
                (im < 0.0 ? '-' : '+'), Math.abs(im));
        }
    }

    private static Complex[] quadraticRoots(double a, double b, double c) {
        Complex[] roots = new Complex[2];
        double d = b * b - 4.0 * a * c;