using System;

public class Program

{

    public static void Main()

    {

        int firstangle = 0;

        //This assigns the value of zero to the variable that represents the first angle of the triangle

        int secondangle = 0;

        //This assigns the value of zero to the variable that represents the second angle of the triangle

        int thirdangle = 0;

        //This assigns the value of zero to the variable that represents the third angle of the triangle

        int sum;

        //This declares the varibale to represent the sum of the three angles

        switch (firstangle)

        {

            case 1:

                Console.WriteLine("Enter a value for the first angle:");

                //This asks the user to enter a number for the first angle 

                firstangle = Convert.ToInt32(Console.ReadLine());

                //This takes the number entered by the user 

                break;

                //This ends the case for the first angle 

        }

        switch (secondangle)

        {

            case 1:

                Console.WriteLine("Enter a value for the second angle:");

                //This asks the user to enter a number for the second angle

                secondangle = Convert.ToInt32(Console.ReadLine());

                //This takes the number entered by the user 

                break;

                //This ends the case for the second angle 

        }

        switch (thirdangle)

        {

            case 1:

                Console.WriteLine("Enter a value for the third angle:");

                //This asks the user to enter a number for the third angle

                firstangle = Convert.ToInt32(Console.ReadLine());

                //This takes the number entered by the user 

                break;

                //This ends the case for the third angle

        }

        sum = firstangle + secondangle + thirdangle;

        //This assigns the sum of all three angles to the variable representing the sum

        if (sum == 180)

        {

            Console.WriteLine("The triangle is valid");

            //This displays to the screen only if the sum of the three angles is equal to 180

        }

        else

        {

            Console.WriteLine("The triangle is not valid");

            //This displays to the screen only if the sum of the three angles is not equal to 180

        }

    }

}

​