NumbersInIntervalDividableby5

class NumbersInIntervalDividableby5
    {
        static void Main()
        {
            int start = int.Parse(Console.ReadLine());
            int end = int.Parse(Console.ReadLine());

            int realStart = (start / 5) * 5 + 5;
            int realEnd = (end / 5) * 5;
            int count = (realEnd - realStart) / 5 + 1;
            Console.WriteLine(start % 5 == 0 ? ++count : count);
        }
    }