Astrological Digits

using System;

//The astrological digit of a given number N is a digit calculated by the number's digits by a special algorithm. The algorithm performs the following steps:
//(1)   Sums the digits of the number N and stores the result back in N.
//(2)   If the obtained result is bigger than 9, step (1) is repeated, otherwise the algorithm finishes.
//The last obtained value of N is the result, calculated by the algorithm.
//Input
//The input data should be read from the console.
//The only line in the input contains a number N, which can be integer or real number (decimal fraction).
//The input data will always be valid and in the format described. There is no need to check it explicitly.
//Output
//The output data should be printed on the console.
//You must print the calculated astrological digit of the number N on the first and only line of the output.

class Program
{
    static void Main()
    {
        string num = Console.ReadLine();
        int sum = new int();
        foreach(char digit in num)
        {
            if ((digit != '.')&&(digit != '-'))
            {
                sum += digit - '0';
            }
        }

        if (sum % 9 == 0 && sum != 0)
        {
            Console.WriteLine(9);
        }
        else
        {
            Console.WriteLine(sum % 9);
        }
    }
}