Trailing Zeros

using System;
using System.Numerics;

class Zeros
{
    static void Main()
    {
        int number = int.Parse(Console.ReadLine());

        BigInteger factorial = 1;
        int count = 0;

        for (int i = 1; i <= number; i++)
        {
            factorial = i * factorial;
        }
        Console.WriteLine(factorial);

        BigInteger digit = factorial % 10;

        while (digit == 0)
        {
            count++;
            factorial /= 10;
            digit = factorial % 10;
        }

        Console.WriteLine("trailing zeros = {0}", count);
    }
}