#include <iostream>
#include <vector>
#include <cstring>
#include <string>
#include <algorithm>
#include <iomanip>
#include <cmath>
#include <cassert>
using namespace std;
typedef long double ld;
const int MAX = 1000;
ld dp[MAX + 10][101][2];

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	int p0, q;
	cin >> p0 >> q;

	ld ans = 1.0 / 3.0;

	dp[0][p0][0] = 1.0 / 3.0;
	for(int i = 0; i < MAX; i++) {
		for(int j = 0; j <= 100; j++) {
			for(int k = 0; k < 2; k++) {
				if(dp[i][j][k] == 0) continue;
				// use
				ans += j / 100.0 * dp[i][j][k] / 2;
				dp[i + 1][max(0, j - q)][1] += j / 100.0 * dp[i][j][k] / 2;
				// not use
				ans += (100 - j) / 100.0 * dp[i][j][k] / 3;
				dp[i + 1][min(100, j + q)][0] += (100 - j) / 100.0 * dp[i][j][k] / 3;
			}
		}
	}

	cout << setprecision(15) << ans << endl;
}