#include <iostream>
#include <iomanip>
using namespace std;

double table[1000][101];
bool used[1000][101];

int p0, q;

double solve(int times, int p) {
    if (used[times][p]) {
        return table[times][p];
    }
    if (times == 200) {
        used[times][p] = true;
        return table[times][p] = 1.0 / 3.0;
    }
    used[times][p] = true;
    double res;
    if (times == 0) {
        res = 1 / 3.0 + 1 / 3.0 * (solve(times + 1, p));
    } else {
        res = (double)p / 100.0 * (0.5 + 0.5 * solve(times + 1, max(p - q, 0))) +
                        (double)(100 - p) / 100.0 * (1 / 3.0 + 1 / 3.0 * solve(times + 1, min(p + q, 100)));
    }
    return table[times][p] = res;
}

int main() {
    cin >> p0 >> q;
    cout << fixed << setprecision(10) << solve(0, p0) << endl;

    return 0;
}