I encounter a error when I try to convert a string variable which is read from a text file to int.
How can I convert the number that is read from a text to int?

```
namespace ConsoleApp1
{
    class FileWriter
    {
        static void Main()
        {
            int a = 6;
            StreamWriter writer = new StreamWriter(@"D:\asd.txt");
            using (writer)
            {
               writer.WriteLine(a);
            }
        }
    }
}
class FileReader
{
     static void Second()
     {
        StreamReader reader = new StreamReader(@"D:\asd.txt");
        using (reader)
        {

            string line = reader.ReadLine();
            Console.WriteLine(line);

           }

            );

    }

    }

```