public class UrnProblem {

    public static void main (String[] argv)
    {
	double total = 0;
	int n = 10000;
	for (int i=0; i<n; i++) {
	    total += numDrawingsNeeded ();
	}
	double avg = total/n;
	System.out.println (avg);
    }

    static int numDrawingsNeeded ()
    {
	// Return the number of drawings needed
	// so that each color is drawn at least once.
    }


    // This method returns 1, 2 or 3, depending
    // on whether a red (1), blue (2) or green (3)
    // was selected.

    static int chooseBall ()
    {
	int k = random (1, 6);
	if (k==1) {
	    return 1;
	}
	else if ( (k==2) || (k==3) ) {
	    return 2;
	}
	else {
	    return 3;
	}
    }

    static int random (int a, int b)
    {
	if (b < a) {
	    return 0;
	}
	double r = (b-a+1) * Math.random ();
	int k = (int) Math.floor (r);
	return (a + k);
    }

}