using System;

public class Program

{

    public static void Main()

    {

        var number = new HappyNumber(19);

        Console.WriteLine(string.Format("Is happy number: {0}", number.isHappy()));

    }

    public class HappyNumber{

        protected int Number;

        public HappyNumber(int number) {

            Number = number;

        }

        protected int digitSquareSum(int n) {

            int sum = 0, tmp;

            while (n != 0) {

                tmp = n % 10;

                sum += tmp * tmp;

                n /= 10;

            }

            return sum;

        }       

        public bool isHappy() {

            int slow, fast;

            slow = fast = Number;

            do {

                slow = digitSquareSum(slow);

                fast = digitSquareSum(fast);

                fast = digitSquareSum(fast);

                if(fast == 1) return true;

            } while(slow != fast);

             return false;

        }       

    }

}