import java.util.*;
import java.io.*;
import java.lang.Math;


public class AntiQS {
    FastScanner in;
    PrintWriter out;


    public double binSearch(double a, int n) {
        double low = 0;
        double high = a;
        while (ans(a, high, n) - ans(a, low, n) > 0.001) {
            double m = (high - low) / 2;
            if (!touch(a, m, n)) {
                high = m;
            } else {
                low = m;
            }
        }
        return ans(a, high, n);
    }

    public double ans(double a, double b, int n) {
        boolean f = true;
        double[] E = new double[n];
        E[0] = a;
        E[1] = b;
        for (int i = 2; i < n; i++) {
            E[i] = ((E[i - 1] + 1) * 2) - E[i - 2];
            if (E[i] < 0) f = false;
        }
        return E[n - 1];
    }

    public boolean touch(double a, double b, int n) {
        boolean f = true;
        double[] E = new double[n];
        E[0] = a;
        E[1] = b;
        if (a <= 0 || b <= 0) {
            return false;
        }
        for (int i = 2; i < n; i++) {
            E[i] = ((E[i - 1] + 1) * 2) - E[i - 2];
            if (E[i] <= 0) f = false;
        }
        return f;
    }

    public void solve() throws IOException {
        int n;
        double a;
        a = Double.parseDouble(in.next());
        n = in.nextInt();
        double t = binSearch(a, n);
        out.print(t);
    }

    public void run() {
        try {
            in = new FastScanner(new File("style.in"));
            out = new PrintWriter(new File("style.out"));

            solve();

            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        FastScanner(File f) {
            try {
                br = new BufferedReader(new FileReader(f));
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }

        String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }
    }

    public static void main(String[] arg) {
        new AntiQS().run();
    }
}