How to solve problem CS0161 in C#?

Question

C++ / C#

Hey!

I am new to C# and have recently started learning about functions. I need to make a program that asks for numbers, a sign and performs an action (the calculator is shorter). But I ran into a problem, here's what it sounds like:
Severity Code Description Project File String Suppression Status
Error CS0161 '"Program.Nikita(int, int, char)": not all code paths return a value.
here is the program code:

public static int Nikita(int a, int b, char d)
        {
            switch (d)

            {
                case '+':
                  return a + b;
                case '-':
                  return a - b;
                case '*':
                  return a * b;
                case '/':
                  return a / b;
                default:
                   Console.WriteLine("Ошибка");
                   break;


            }
            //return a - b;
        }
        static void Main(string[] args)
        {   
            {
                Console.Write("вевдите первое число: ");
                int am = (int)Convert.ToInt64(Console.ReadLine());
                Console.Write("введите знак: ");
                char dm = Convert.ToChar(Console.ReadLine());
                Console.Write("введите второе число: ");
                int bm = (int)Convert.ToInt64(Console.ReadLine());
                int resault = Nikita(am, bm, dm);
                Console.WriteLine(am);
                Console.WriteLine(bm);
                Console.WriteLine(dm);
                Console.WriteLine(resault);

            }
        }
    }
}

Answer 1

Well, they even write to you in Russian (by the way, switch to English. And wrap the code in a code tag) ...
What should the Nikita function return if I pass 'q' as the third parameter, for example?
A function with a return parameter must ALWAYS return a value. Or throw an exception.

Answer 2

Uncommentreturn a - b;