using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Enter array of numbers:");

        string line = Console.ReadLine();

        string[] numbers = line.Trim().Split(',');

        Console.WriteLine("Enter your number: ");

        string number = Console.ReadLine();

        double probability = (double)numbers.Count(num => num == number) / numbers.Length;

        Console.WriteLine(probability);

    }

}