package no425;

import java.util.Scanner;

public class Main {

	static int N = 1000;
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int p0 = sc.nextInt();
		int q = sc.nextInt();
		double[][] dp = new double[N+1][101];
		dp[1][p0] = 1D / 3;
		double ans = 1D / 3;
		for(int i=1;i<N;i++) {
			for(int j=0;j<=100;j++) {
				if (dp[i][j] == 0) continue;
//				System.out.println(i + "," + j + ":" + dp[i][j]);
				//使う
				ans += dp[i][j] * j / 100 / 2;
				dp[i+1][Math.max(j - q, 0)] += dp[i][j] * j / 100 / 2;
				//使わない
				ans += dp[i][j] * (100 - j) / 100 / 3;
				dp[i+1][Math.min(j + q, 100)] += dp[i][j] * (100 - j) / 100 / 3;
			}
		}
		System.out.println(String.format("%.7f", ans));
	}

}