# include <iostream>
# include <algorithm>
# include <vector>
# include <string>
# include <set>
# include <map>
# include <cmath>
# include <iomanip>
# include <functional>
# include <utility>
# include <stack>
# include <queue>
# include <list>
# include <tuple>
# include <unordered_map>
# include <numeric>
# include <complex>
# include <bitset>
# include <random>
# include <chrono>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
constexpr int INF = 2147483647;
constexpr int HINF = INF / 2;
constexpr double DINF = 100000000000000000.0;
constexpr double HDINF = 50000000000000000.0;
constexpr long long LINF = 9223372036854775807;
constexpr long long HLINF = 4500000000000000000;
const double PI = acos(-1);
int dx[4] = { 0,1,0,-1 }, dy[4] = { 1,0,-1,0 };
template <typename T_char>T_char TL(T_char cX) { return tolower(cX); };
template <typename T_char>T_char TU(T_char cX) { return toupper(cX); };
# define ALL(x)      (x).begin(),(x).end()
# define UNIQ(c)     (c).erase(unique(ALL((c))),(c).end())
# define LOWER(s)    transform(ALL((s)),(s).begin(),TL<char>)
# define UPPER(s)    transform(ALL((s)),(s).begin(),TU<char>)
# define mp          make_pair
# define eb          emplace_back
# define FOR(i,a,b)  for(LL i=(a);i<(b);i++)
# define RFOR(i,a,b) for(LL i=(a);i>=(b);i--)
# define REP(i,n)    FOR(i,0,n)
# define INIT        std::ios::sync_with_stdio(false);std::cin.tie(0)

double dp[3][2000];
double s[2000];
double memo[2000][2000];
int m;

int main() {
	cin >> m;
	REP(i, pow(2, m)) {
		cin >> s[i];
		dp[0][i] = 1.0;
	}
	
	REP(i, pow(2, m)) {
		REP(j, pow(2,m)){
			memo[i][j] = (s[i] * s[i]) / (s[i] * s[i] + s[j] * s[j]);
		}
	}
	int mask = pow(2,m+2)-1;
	for (int i = 0; i < m; i++) {
		mask -= 1 << i;
		REP(j, 1 << m) {
			REP(k, 1 << m) {
				if ((j&mask) == (k&mask) && ((j^k)&(1 << i)))dp[i + 1][j] += dp[i][k] * memo[j][k];
			}
			dp[i + 1][j] *= dp[i][j];
		}
	}
	cout << fixed << setprecision(13) << dp[m][0] << endl;
	//system("pause");
}