#include <algorithm>
#include <array>
#include <cassert>
#include <cmath>
#include <iostream>
#include <utility>
#include <vector>

int main() {
    using namespace std;
    constexpr int N = 101;
    constexpr double EPS = 1e-12;
    using Mat = array<array<double, N>, N>;
    using Vec = array<double, N>;

    // Ab + c = b を満たす b を求める
    auto solve = [&](const Mat &A, const Vec &c) -> Vec {
        Mat mat{};
        Vec b{};

        for (int i = 0; i < N; i++) {
            for (int j = 0; j < N; j++) {
                mat[i][j] = (i == j ? 1.0 : 0.0) - A[i][j];
            }
            b[i] = c[i];
        }

        for (int j = 0; j < N; j++) {
            int piv = j;
            for (int i = j + 1; i < N; i++) {
                if (abs(mat[i][j]) > abs(mat[piv][j])) { piv = i; }
            }
            assert(abs(mat[piv][j]) >= EPS);
            swap(mat[j], mat[piv]);
            swap(b[j], b[piv]);

            const double inv = 1.0 / mat[j][j];
            for (int i = j + 1; i < N; i++) {
                const double t = mat[i][j] * inv;
                mat[i][j] = 0.0;
                for (int k = j + 1; k < N; k++) {
                    mat[i][k] -= mat[j][k] * t;
                }
                b[i] -= t * b[j];
            }
        }

        for (int i = N - 1; i >= 0; i--) {
            double s = b[i];
            for (int j = i + 1; j < N; j++) {
                s -= mat[i][j] * b[j];
            }
            b[i] = s / mat[i][i];
        }
        return b;
    };

    int p, q;
    cin >> p >> q;
    Mat A{};
    Vec c{};
    for (int i = 0; i < N; i++) {
        if (i > 0) { A[i][max(0, i - q)] += 1.0 * i / 200; }
        if (i < N - 1) { A[i][min(N - 1, i + q)] += (100.0 - i) / 300; }
        c[i] = 1.0 / 3 + 1.0 * i / 600;
    }
    Vec b = solve(A, c);
    double ans = 1.0 / 3 + b[p] / 3;
    cout << format("{:.15f}\n", ans);
}