#include<cstdio>
#include<math.h>
#include<iostream>
#define MAXN 100002
#define int long long
using namespace std;
int n;
double c;
double MOD = 900000011.0;
double x;
void findX()
{
    double d = (double)(c * c) - 4.0;
    d = sqrt(d);
    //cout<<d<<endl;
    x = ((double)(c) + d) / 2.0;
}
double power(double x, int y)
{
    double res = 1.0;
    while (y > 0)
    {
        //cout<<y<<endl;
        if (y % 2 == 1) res = (res * x);
        y = y >> 1;
        x = (x * x);
        while(x > MOD) x -= MOD;
        while(res > MOD) res -= MOD;
    }
    return res;
}
signed main()
{
    freopen("equation.in", "r", stdin);
    freopen("equation.out", "w", stdout);
    scanf("%lld", &n);
    scanf("%lf", &c);
    findX();
    //cout<<x<<endl;
    double xn = power(x, n);
    //cout<<xn<<endl;
    double ans = xn + (xn - 1.0) / (x - 1) + (xn - 1.0) / ((xn) * (x - 1.0));
    printf("%lf\n",ans);
    return 0;
}