4.11.Numbers in Interval Dividable by Given Number

using System;

class DivideByGivenNumber
{
    static void Main()
    {
        int firstN = int.Parse(Console.ReadLine());
        int seconfN = int.Parse(Console.ReadLine());
        int dif = seconfN - firstN;
        int sum = 0;
        for (int i = firstN; i <= seconfN; i++)
        {
            if (i % 5 == 0)
            {
                sum += 1; ;
            }
        }
        Console.WriteLine("p= {0}", sum);
    }
}