namespace E_FactorialTrailingZeroes

{

    using System;

    using System.Numerics;

​

    public class FactorialZeroes

    {

        public static void Main()

        {

            var number = int.Parse(Console.ReadLine());

            GetFactorial(number);

        }

​

        public static void GetFactorial(int number)

        {

            BigInteger factorial = 1;

​

            for (int i = 1; i <= number; i++)

            {

                factorial *= i;

            }

​

            GetTrailingZeroes(factorial);

        }

​

        public static void GetTrailingZeroes(BigInteger factorial)

        {

            var counter = 0;

            for (int i = 0; i < factorial.ToString().Length; i++)

            {

                if (factorial % 10 == 0)

                {

                    counter++;

                    factorial /= 10;

                }

                else

                {

                    break;

                }

            }

​

            Console.WriteLine(counter);

​

            //if (counter == 1)

            //{

            //    return "One trailing zero";

            //}

​

            //else

            //{

            //    return counter + " trailing zeroes";

            //}

        }

    }

}