/* @JUDGE_ID: 32472GK 1066 C++ */
#include <iostream>
#include <vector>
#include <string>
#include <cstdio>
#include <cstdlib>
#include <map>
#include <algorithm>
#include <climits>
#include <cctype>
#include <cassert>
using namespace std;

typedef pair<double, double> poly;

double solve(int N, double A)
{
  vector<poly> y(N);
  y[0] = poly(0, A);
  y[1] = poly(1, 0);
  for (int i = 2; i < N; ++i) {
    double a = y[i - 1].first;
    double b = y[i - 1].second;
    double c = y[i - 2].first;
    double d = y[i - 2].second;
    y[i] = poly(2 * a - c, 2 * b - d + 2);
  }

  double an = y[N - 1].first;
  double bn = y[N - 1].second;
  for (int i = 0; i < N; ++i) {
    double c = y[i].first;
    double d = y[i].second;
    y[i] = poly(c / an, - bn * c / an + d);
  }

  double x = 0.0;
  for (int i = 0; i < N; ++i) {
    double a = y[i].first;
    double b = y[i].second;
    x = max(x, - b / a);
  }

  return x;
}


int main()
{
  int N;
  double A;
  cin >> N >> A;

  char buf[50];
  double d = solve(N, A);
  sprintf(buf, "%.2f", d);
  cout << buf << endl;
}