//
//	1/2 + 1/4 + ... + 1/100 = ?
//
//	Recusion
//

class RecursionFractionSum2

{
	public static double s(double n)
	{
		if (n==1) return 1.0/2;
		else
				return s(n-1)+1.0/(2*n);
	}
	public static void main(String[] args)
	{
		double ans = s(50);	// 2.5


		System.out.println("s = " + ans);

		System.out.println("\n\nDone.\n\n");
	}
}