Factorial Calculator in C#

using System;
namespace Factorial
{
class Project1
{
void Main()
{
int x,f;
Console.Write("Enter a positive number : ");
x=Convert.ToInt32(Console.ReadLine());
f=x;
while((x-1)>0){
f=f*(x-1);
x--;}
Console.Write("The factorial is {0}",f);
}
}
}