What do I need to change in this program?

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace ConsoleApp3

{

class Program

{

static void Main(string[] args)

{

int num1 = 0, num2 = 0;

char c = 'a';

//double result = 0;

Console.WriteLine("Please enter 2 numbers:");

num1 = int.Parse(Console.ReadLine());

num2 = int.Parse(Console.ReadLine());

Console.WriteLine("Please enter the operation sign:");

c = char.Parse(Console.ReadLine()); /

Calc (num1,num2,c); //

}

public static void Calc (int a, int b, char c) //

{

double result = 0;

int num1 = 0; int num2 = 0;

char sign ='a';

switch (sign)

{

case '+':

result = num1 + num2; break;

case '-':

result = num1 - num2; break;

case '*':

result = num1 * num2; break;

case '/':

result = num1 / num2; break;

}

if (result != 0)

Console.Write(result);

else

Console.Write("This is wrong");

Console.ReadKey();

}