using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;

class TEST{
	static void Main(){
		Sol mySol =new Sol();
		mySol.Solve();
	}
}

class Sol{
	public void Solve(){
		
		double win = 1.0/3.0;
		double[][] dp = new double[2][];
		for(int i=0;i<2;i++)dp[i] = new double[101];
		dp[0][P0] = 1.0/3.0;
		double eps = 1e-9;
		
		for(int t=0;t<(int)5e4;t++){
			
			double[][] nxt = new double[2][];
			for(int i=0;i<2;i++)nxt[i] = new double[101];
			
			for(int i=0;i<101;i++){
				//if(dp[0][i] < eps)continue;
				win += dp[0][i] * 0.5 * (i/100.0);
				nxt[1][Math.Max(0,i-Q)] += dp[0][i] * 0.5 *(i/100.0);
				
				win += dp[0][i] * (1.0/3.0) * (1.0 - (i/100.0) );
				nxt[0][Math.Min(100,i+Q)] += dp[0][i] * (1.0/3.0) *(1.0-(i/100.0));
			}
			for(int i=0;i<101;i++){
				//if(dp[1][i] < eps)continue;
				win += dp[1][i] * 0.5 * (i/100.0);
				nxt[1][Math.Max(0,i-Q)] += dp[1][i] * 0.5 *(i/100.0);
				
				win += dp[1][i] * (1.0/3.0) * (1.0 - (i/100.0) );
				nxt[0][Math.Min(100,i+Q)] += dp[1][i] * (1.0/3.0) *(1.0-(i/100.0));
			}
			
			dp = nxt;
		}
		
		Console.WriteLine(win);
		
	}
	int P0,Q;
	public Sol(){
		var d = ria();
		P0 = d[0];
		Q = d[1];
	}

	static String rs(){return Console.ReadLine();}
	static int ri(){return int.Parse(Console.ReadLine());}
	static long rl(){return long.Parse(Console.ReadLine());}
	static double rd(){return double.Parse(Console.ReadLine());}
	static String[] rsa(char sep=' '){return Console.ReadLine().Split(sep);}
	static int[] ria(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>int.Parse(e));}
	static long[] rla(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>long.Parse(e));}
	static double[] rda(char sep=' '){return Array.ConvertAll(Console.ReadLine().Split(sep),e=>double.Parse(e));}
}