#include <bits/stdc++.h>
using namespace std;
double p[10][1<<10];
double calc(double a,double b){	return a*a/(a*a+b*b);	}
int main(){
	int m;	cin>>m;
	double s[1<<m];
	for(int i=0;i<(1<<m);i++)	cin>>s[i];
	for(int i=0;i<(1<<m);i+=2){
		p[0][i]=calc(s[i],s[i+1]);	p[0][i+1]=1-p[0][i];
	}
	for(int i=1;i<m;i++){
		for(int j=0;j<(1<<m);j++){
			int num=(j>>i);
			if(num%2==0){
				for(int k=((num+1)<<i);k<((num+2)<<i);k++){
					p[i][j]+=calc(s[j],s[k])*p[i-1][k];
				}
			}
			else{
				for(int k=((num-1)<<i);k<(num<<i);k++){
					p[i][j]+=calc(s[j],s[k])*p[i-1][k];
				}
			}
			p[i][j]*=p[i-1][j];
		}
	}
	printf("%.15lf\n",p[m-1][0]);
	return 0;
}