using System;

namespace gptb2

{               

    public class Program

    {

        static double a,b,c;

        static double delta;

        static double x1,x2;

        static void NhapABC()

        {

            String buf;

            Console.Write("Nhap a : ");

            buf= Console.ReadLine();

            a = Double.Parse(buf);

            Console.Write("Nhap b : ");

            buf= Console.ReadLine();

            b = Double.Parse(buf);

            Console.Write("Nhap c : ");

            buf= Console.ReadLine();

            c = Double.Parse(buf);

        }

        static void GiaiPT()

        {

            delta = b*b-4*a*c;

            if (delta >= 0)

            {

                 x1=(-b + Math.Sqrt(delta))/2/a;

                 x2=(-b - Math.Sqrt(delta))/2/a;

            }

        }

        static void XuatKQ()

        {

            if (delta <0)

                Console.WriteLine("Phuong trinh vo nghiem ");

            else 

            {

                Console.WriteLine("Phuong trinh co 2 nghiem thuc: ");

                Console.WriteLine("X1 = " + x1);

                Console.WriteLine("X2 = " + x2);

            }

        }

        public static void Main()

        {

            NhapABC();

            GiaiPT();

            XuatKQ();

            Console.ReadKey();

        }

    }

}