public class Program
{
    public static void Main()
    {
        int num = int.Parse(Console.ReadLine() ?? string.Empty);
        //string[] str = (Console.ReadLine() ?? string.Empty).Trim().Split(' ');
        //string str = Console.ReadLine() ?? string.Empty;

        //if(num == 2 || num == 3||num == 5||num==7|| num == 11||num== 13 ||num ==4||num == 6
        //    ||num == 9 || num == 10)
        //{
        //    Console.WriteLine(0.00000000000000000);
        //}

        int[] so = {2,3,5,7,11,13};
        int[] go = { 4, 6, 8, 9, 10, 12 };

        int count = 0;
        for(int i = 0; i < so.Length; i++)
        {
            for(int j = 0; j < go.Length; j++)
            {
                int ans = so[i] * go[j];
                if(ans == num)
                {
                    count++;
                }
            }
        }
        double aaa = (double)count / 36;
        Console.WriteLine(aaa);
    }
}