#define FNAME "garland"
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <string>
#include <map>
#include <vector>
#include <iomanip>

using namespace std;

const int N = 2e3;
double h[N];

int main() {
#ifdef _DEBUG
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#else
    freopen(FNAME".in", "r", stdin);
    freopen(FNAME".out", "w", stdout);
#endif
    ios::sync_with_stdio(false);

    int n, i;
    cin >> n >> h[0];

    double l = 0, r = h[0] * n;
    for (int it = 0; it < 10000; ++it) {
        double m = (l + r) / 2;
        h[1] = m;
        for (i = 2; i < n; ++i) {
            h[i] = (h[i - 1] + 1) * 2 - h[i - 2];
            if (h[i] <= 0) {
                l = m;
                break;
            }
        }
        if (i == n) {
            r = m;
        }
    }

    h[1] = r;
    for (i = 2; i < n; ++i) {
        h[i] = (h[i - 1] + 1) * 2 - h[i - 2];
    }

    cout << setprecision(2) << fixed << h[n - 1] << "\n";
    return 0;
}