using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ForLessons
{
    /*
     *  persistence(39) == 3    // because 3*9 = 27, 2*7 = 14, 1*4=4
                                // and 4 has only one digit

        persistence(999) == 4   // because 9*9*9 = 729, 7*2*9 = 126,
                                // 1*2*6 = 12, and finally 1*2 = 2

        persistence(4) == 0     // because 4 is already a one-digit number
     * */
    class Program
    {
        static void Main(string[] args)
        {

        }
        public static int Persistence(long n)
        {
            // your code

            return 0;
        }
    }
}