using System;

class QuadraticEquation
{
    static void Main()
    {
        Console.Write("Enter 'a': ");
        double a = double.Parse(Console.ReadLine());
        Console.Write("Enter 'b': ");
        double b = double.Parse(Console.ReadLine());
        Console.Write("Enter 'c': ");
        double c = double.Parse(Console.ReadLine());

        double discriminant = Math.Pow(b, 2) - (4 * a * c);

        double x1;
        double x2;

        if (a == 0)
        {
            Console.WriteLine("'a' must not be '0'");
        }

        else if (discriminant > 0 && a != 0)
        {
            x1 = ((-b) - (Math.Sqrt(discriminant))) / (2 * a);
            x2 = ((-b) + (Math.Sqrt(discriminant))) / (2 * a);
            Console.WriteLine("x1 = {0}; x2 = {1}", x1, x2);
        }

        else if (discriminant == 0 && a != 0)
        {
            x1 = x2 = -(b / (2 * a));
            Console.WriteLine("x1 = x2 = {0}", x1);
        }

        else
        {
            Console.WriteLine("no real roots");
        }
    }
}