using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Apps Selection");

        Console.WriteLine("1 : Pythagoras Theorem");

        Console.WriteLine("2 : BMI Calculator");

        Console.WriteLine("3 : Quadratic Equation ");

        Console.WriteLine("4 : Cartension Quadrant Checker ");

        int choice = Convert.ToInt32(Console.ReadLine());

        if (choice == 1)

        {

            Console.WriteLine("Pythagoras Theorem");

        Console.WriteLine("a^2 + b^2 = c^2");

        Console.Write("a = ");

        double a = Convert.ToDouble(Console.ReadLine());

        Console.Write("b = ");

        double b = Convert.ToDouble(Console.ReadLine());

        Console.WriteLine("c = " + Math.Sqrt(a * a + b * b));

        }

        else if (choice == 2)

        {

            Console.WriteLine("BMI Calculator");

        Console.Write("User weight (in kg)  : ");

        double weight = Convert.ToDouble(Console.ReadLine());

        Console.Write("User height (in m)  : ");

        double height = Convert.ToDouble(Console.ReadLine());

        double bmi = weight / (height * height); 

        Console.WriteLine("User BMI result : " + bmi);

        if (bmi < 16)

            {

            Console.WriteLine("Category : Severe Thinness ");

        }

        else if ((bmi >= 16 ) && (bmi < 17))

            { 

             Console.WriteLine("Category : Moderate Thinness");

        }

        else if ((bmi >= 17 ) && (bmi < 18.5))

            { 

             Console.WriteLine("Category : Mild Thinness");

        }

        else if ((bmi >= 18.5 ) && (bmi < 25))

            { 

             Console.WriteLine("Category : Normal");

        }

        else if ((bmi >= 25 ) && (bmi < 30))

            { 

             Console.WriteLine("Category : Overweight ");

        }

        else if ((bmi >= 30 ) && (bmi < 35))

            { 

             Console.WriteLine("Category : Obese Class 1");

        }

        else if ((bmi >= 35 ) && (bmi < 40))

            { 

             Console.WriteLine("Category : Obese Class 2");

        }

        else if (bmi >= 40)

            { 

             Console.WriteLine("Category : Obese Class 3");

        }

        }

        else if (choice == 3)

        {

            Console.WriteLine("Quadratic Equation ");

        Console.WriteLine("ax² + bx + c = 0");

        Console.WriteLine("Example :");

        Console.WriteLine("3x² + 9x + 5 = 0");

        Console.WriteLine("where a=3, b=9, c=5");

        Console.Write("a = ");

        double a = Convert.ToDouble(Console.ReadLine());

        Console.Write("b = ");

        double b = Convert.ToDouble(Console.ReadLine());

        Console.Write("c = ");

        double c = Convert.ToDouble(Console.ReadLine());

        double result = ((b*b) - (4*a*c));

        Console.WriteLine("b² + 4ac = " + result); 

        if (result == 0)

            {Console.WriteLine("1 root (1 interception point with X-axis )");

        }

        else if (result <0)

            {Console.WriteLine("Imaginary root (0 interception point with X-axis )");

        }

        else if (result >0)

            {Console.WriteLine("2 roots (2 interception point with X-axis )");

        }

        }

        else if (choice == 4)

        {

            Console.WriteLine("Checking Cartension Quadrant ");

        Console.Write("Coordinate X : ");

        double x = Convert.ToDouble(Console.ReadLine()); 

        Console.Write("Coordinate Y : ");

        double y = Convert.ToDouble(Console.ReadLine());

        if ((x > 0) & (y > 0))

        {

        Console.WriteLine("Quadrant 1");

        }

        else if ((x < 0) & (y > 0))

        {

        Console.WriteLine("Quadrant 2");

        }

        else if ((x < 0) & (y < 0))

        {

        Console.WriteLine("Quadrant 3");

        }

        else if ((x > 0) & (y < 0))

        {

        Console.WriteLine("Quadrant 4");

        }

        else if (((x < 0)||(x > 0)) & (y == 0))

        {

        Console.WriteLine("Coordinate lies on X-axis ");

        }

        else if (((y < 0)||(y > 0)) & (x == 0))

        {

        Console.WriteLine("Coordinate lies on Y-axis ");

        }

        else if ((x == 0) & (y == 0))

        {

        Console.WriteLine("Origin");

        }

        }

    }

}