double x, y;
            char sb;
            do
            {
                Console.WriteLine("Add x");
                x = double.Parse(Console.ReadLine());
                Console.WriteLine("Add y");
                y = double.Parse(Console.ReadLine());
                if (x >= 0)
                    if ((x * x + y * y <= 4) && (y <= x))
                        Console.WriteLine("G = F({0},{1}), true", x, y);
                    else Console.WriteLine("G = F({0},{1}), false", x, y);
                else Console.WriteLine("G = F({0},{1}), false", x, y);
                Console.WriteLine("To repeat press 1");
                sb = char.Parse(Console.ReadLine());
            } while (sb == '1');