public static void Main()
double a = double.Parse(Console.ReadLine());
double b = double.Parse(Console.ReadLine());
double c = double.Parse(Console.ReadLine());
double smqtane = D = b * b - 4 * a * c ;
double x1 = (-b + Math.Sqrt(D))/(2*a);
double x2 = (-b - Math.Sqrt(D))/(2*a);