#include<cstdio>

#include<cstring>

#include<algorithm>

#define maxn 32

using namespace std;

int n;

double p[maxn],t;

void pre()

{

    p[]=;

    for(int i=;i<=;i++)

        p[i]=p[i-]*2.0;

}

double solve()

{

    double f=p[n];

    for(int i=n-;i>=;i--)

    {

        double eq=p[i]/f;

        if(eq<t)

            f=(+t)*f/2.0;

        else

            f=(eq-t)*p[i]/(-t)+(-eq)*(eq+)*f/(-t)/2.0;

    }

    return f;

}

int main()

{

    pre();

    while(scanf("%d%lf",&n,&t)&&n)

    {

        printf("%.3lf\n",solve());

    }

    return ;

}