Hexadecimal To Decimal

using System;

class HexademicalToDecimal
{
    static void Main()
    {
        string hex = Console.ReadLine();
        long resultindecimal = 0;
        int element = 0;

        for (int i = hex.Length - 1; i >= 0; i--)
        {
            if (hex[i] > '9')
            {
                element = hex[i] - '7';
                // example: 'A' = 65 (ASCII code); '7' = 55; hence 'A' - '7' = 10,
                // which is exactly the decimal representation of the digit A
            }
            else
            {
                element = hex[i] - '0';
            }

            resultindecimal += element * PowerOf(hex.Length - (i + 1));

        }
        Console.WriteLine(resultindecimal);


    }
    static long PowerOf(int grade)
    {
        long result = 1;
        int poweredNum = 16;
        for (int i = 1; i <= grade; i++)
        {

            result *= poweredNum;
        }

        return result;
    }
}