#include <bits/stdc++.h>
using namespace std;

int main(){
    double x;int n;
    while(cin>>x>>n){
        std::vector<double> a(n+1);
        a[0]=x;
        for(int i=1;i<=n;i++){
            a[i]=a[i-1]*2.0/3.0+x/(3.0*a[i-1]*a[i-1]);
        }
        printf("%.6lf\n",a[n]);
    }
}