method problems

Question

I want to calculate a factorial(n!) input as an interger "n"

I found there is an error at Fact(n); 

error says 

The name 'n' does not exist int the current context 

what`s wrong with the n in Fact() method?

 

 

 

---

 

 

 

public static void Main()

{

Console.WriteLine("Type an integer");

string factorial = Console.ReadLine();

Fact(n);

}

public static void Fact(int n)

 {

   if (n == 0)

      {

         n = 1;

      }

      else if (n >= 1)

      {

      for (int i = 1; i < n; i++)

      {

         n = n * i;

      }

 }