import java.io.PrintStream;
import java.util.Scanner;


public class Y425 {
	int p0;
	int q;
	
	Y425() throws Exception {
		Scanner in = new Scanner(System.in);
		PrintStream out = new PrintStream(System.out);
		
		p0 = in.nextInt();
		q = in.nextInt();
		
		double ans = 1.0 / 3;
		
		ans += dfs(p0, 1.0 / 3);
		
		out.println(ans);
		out.flush();
	}

	double dfs(int p, double s) {
		if (s < 1e-9) return s / 2.0;
		
		double ans = 0;
		ans += p / 100.0 * 0.5 * s;
		ans += dfs(Math.max(0, p - q), p / 100.0 * s * 0.5);
		ans += (100 - p) / 100.0 / 3.0 * s;
		ans += dfs(Math.min(100, p + q), (100 - p) / 100.0 * s / 3.0);
		return ans;
	}
	
	public static void main(String argv[]) throws Exception {
		new Y425();
	}
}