Quadratic Equation

using System;

namespace QuadraticEquation
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.Write("A = ");
            int a = int.Parse(Console.ReadLine());
            Console.Write("B = ");
            int b = int.Parse(Console.ReadLine());
            Console.Write("C = ");
            int c = int.Parse(Console.ReadLine());
            double d = b * b - 4 * a * c;
            double x1, x2;
            if (a == 0)
            {
                if (b == 0 && c == 0)
                {
                    Console.WriteLine("All real numbers are solutions!");
                }
                else if (b == 0 && c != 0)
                {
                    Console.WriteLine("There aren't real roots!");
                }
                else
                {
                    x1 = x2 = -c / b;
                    Console.Write("x = ");
                    Console.WriteLine(x1);
                }
            }
            else
            {
                if (d < 0)
                {
                    Console.WriteLine("There aren't real roots!");
                }
                else if (d == 0)
                {
                    x1 = x2 = -b / 2 * a;
                    Console.Write("x1 = x2 = ");
                    Console.WriteLine(x1);
                }
                else
                {
                    x1 = (-b + Math.Sqrt(d)) / (2 * a);
                    x2 = (-b - Math.Sqrt(d)) / (2 * a);
                    Console.Write("x1 = ");
                    Console.WriteLine(x1);
                    Console.Write("x2 = ");
                    Console.WriteLine(x2);
                }
            }
        }
    }
}