TrailingZeroes

static void Main()
        {
            int number = int.Parse(Console.ReadLine());
            int zeroCount = 0;
            int d;
            for (int i = 5; i <= number; i += 5)
            {
                d = i;
                while (d % 5 == 0)
                {
                    d /= 5;
                    zeroCount++;
                }
            }
            Console.WriteLine(zeroCount);

        }