import java.util.Scanner;

public class Quadratic
{


	public static void main(String[] args)
	{
		Scanner scanner = new Scanner(System.in);

                while(scanner.toString() != "NO")
                {
		try
		{
			System.out.println("Enter A");
			double a = scanner.nextDouble();
			scanner.nextLine();

			System.out.println("Enter B");
			double b = scanner.nextDouble();
			scanner.nextLine();

			System.out.println("Enter C");
			double c = scanner.nextDouble();
			scanner.nextLine();

			root(a,b,c);


			System.out.println("It works!");


		}
		catch (IllegalArgumentException oops)
		{
			oops.printStackTrace();
		}
		catch(Exception other)
		{
			other.printStackTrace();
		}

                System.out.println("Do you want to continue ?");
                System.out.println("YES / NO");
                String a1 = scanner.next();
                }

            System.out.println("Exit");
	}

	static double root(double A, double B, double C) throws IllegalArgumentException
	{
		if (A == 0)
		{
			throw new IllegalArgumentException("A can't be zero");
		}
		else
		{
			double disc = B*B - 4*A*C;
			if (disc < 0)
			{
				throw new IllegalArgumentException("Discriminant < zero.");
			}
			return (-B + Math.sqrt(disc)) / (2*A);
		}
	}
}