// Arup Guha
// 10/24/2016
// Solution to 2016 NCPC Problem F: Fleecing the Raffle

import java.util.*;

public class f {

	public static void main(String[] args) {

		Scanner stdin = new Scanner(System.in);
		int n = stdin.nextInt();
		int k = stdin.nextInt();

		// Probability for 1 ticket.
		int m = 1;
		double res = (double)k/(n+1);

		while (true) {

			// In general, for m tickets, solution is C(n,k-1)*C(m,1)/C(n+m,k).
			// Here I multiply the term for m to obtain the term for m+1;
			double tmp = res*(m+1)/m*(n+m+1-k)/(n+m+1);

			// Better.
			if (tmp > res) res = tmp;

			// Time to get out.
			else break;
			m++;
		}

		System.out.println(res);
	}
}