using System;

​

public class Calculator

{

    public static int Plus(int a, int b)

    {

        int result;

        result = a + b;

        return result;

    }

    public static int Subtract (int a, int b)

    {

        int result;

        result = a - b;

        return result;

    }

    public static int Divide (int a, int b)

    {

        int result;

        result = a / b;

        return result;

    }

    public static int PerformCalculation(string mode, int a, int b)

    {

        if (mode == "Plus")

            return Plus (a, b);

        if (mode == "Subtract")

            return Subtract (a, b);

        else

            return Divide (a, b);

    }

}

public class Program

{

    public static void Main()

    {

        int plusResult = Calculator.Plus(4, 2);

        int subtractResult = Calculator.Subtract(5, 3);

        int divideResult = Calculator.Divide(20, 2);

        Console.WriteLine(plusResult);

        Console.WriteLine(subtractResult);

        Console.WriteLine(divideResult);

    }

}