using System;

public class Program

{

        static int demchusole(int n)

        {

            int dem = 0, d = 0;

            while (n>0)

            {

                d = n % 10;

                if (d%2!=0)

                {

                    dem++;

                }

                n = n / 10;

            }

            return dem;

        }

        static void Main(string[] args)

        {

            Console.WriteLine("Dem so luong chu so le trong so nguyen duong n");

            Console.WriteLine("Nhap so nguyen duong n");

            int n = int.Parse(Console.ReadLine());

            int dem = demchusole(n);

            Console.WriteLine(dem);

        }

}