alalalalalalalalal

#include <iostream>
#include <iomanip>
using namespace std;
double h(double n, double x){
    if(!n){
        return 1.0;
    }else if(n == 1){
        return 2 * x;
    }else{
        return 2 * x * h(n - 1, x) - 2 * (n - 1) * h(n - 2, x);
    }
}
int main(){
    double n, x;
    cin >> n >> x;
    cout << fixed << setprecision(2) << h(n, x);
    return 0;
}