class Program
{
    static void Main(string[] args)
    {
        string[] input = Console.ReadLine()!.Split(' ');
        int min = int.Parse(input[0]);
        int max = int.Parse(input[1]);
        int num = int.Parse(input[2]);
        List<int> numList = new List<int>();
        
        for (int i = min; i <= max; i++)
        {
            int ans = i % num;
            if (numList.Count == 0)
            {
                numList.Add(ans);
            }
            for (int j = 0; j < numList.Count; j++)
            {
                if(ans == numList[j])
                {
                    break;
                }
                else if (j == numList.Count - 1)
                {
                    numList.Add(ans);
                }
            }
        }

        Console.WriteLine(numList.Count);
    }
}