/*
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class Main
{
	public static void main(String[] args)
	{
		Random random = new Random();
		int numExperiments = 10000000;
		int numSuccess = 0;

		List<Integer> sedista = getList();

		for(int i=0;i<numExperiments;++i)
		{
			List<Integer> patnici = getList();
			int pss = 0;

			for (int j=0;j<15;++j)
			{
				if (sedista.get(j) == patnici.remove(random.nextInt(15-j)))
				{
					++pss;
				}
			}

			if (pss > 0)
				++numSuccess;
		}

		System.out.println((double)numSuccess/(double)numExperiments);
		System.out.println(1 - res());
	}

	public static List<Integer> getList()
	{
		List<Integer> patnici = new ArrayList<Integer>();

		for (int i=1;i<=15;++i)
		{
			patnici.add(i);
		}

		return patnici;
	}

	public static int f(int num)
	{
		int result = 1;

		for (int i=1;i<=num;++i)
		{
			result *= i;
		}

		return result;
	}

	public static double res()
	{
		double result = 0;

		for (int i=1;i<=15;++i)
		{
			result += ((double)i/f(i))*Math.pow(-1, i-1);
		}

		return result;
	}
}
*/





import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class Main
{
	public static void main(String[] args)
	{

		Random random = new Random();
		int numExperiments = 10000000; //broj na eksperimenti
		int numSuccess = 0; //kolku pati e uspesen eksperimentot

		for(int i=0;i<numExperiments;++i)
		{
			List<Boolean> cresi = getCresi(); //cresi
			cresi.remove(random.nextInt(15)); //jademe edna od 15 cresi, ostanuvaat 14
			cresi.remove(random.nextInt(14)); //jademe edna od 14 cresi, ostanuvaat 13
			cresi.remove(random.nextInt(13)); //jademe edna od 13 cresi, ostanuvaat 12

			Boolean izbrana = cresi.get(random.nextInt(12)); //birame cresa

			if (izbrana)
				++numSuccess;
		}

		System.out.println((double)numSuccess/(double)numExperiments);
	}

	public static List<Boolean> getCresi()
	{
		/*
		15 cresi
		5 stavame so semka(true)
		10 stavame bez semka(false)
		*/
		List<Boolean> cresi = new ArrayList<Boolean>();
		for(int i=0;i<5;++i)
		{
			cresi.add(true);
		}
		for(int i=0;i<10;++i)
		{
			cresi.add(false);
		}

		return cresi;
	}
}