from collections import *
from itertools import *
from functools import *
from heapq import *
import sys,math
input = sys.stdin.readline

M = int(input())
S = [int(input()) for _ in range(1<<M)]
S = [s**2 for s in S]
N = (1<<M)
dp = [[0]*N for _ in range(M+1)]
dp[0] = [1]*N
for i in range(M):
    D = (1<<(i))

    for j in range(0,N,2*D):
        
        X = []
        Y = []
        for k in range(D):

            X.append((j+k,S[j+k]))
            Y.append((j+k+D,S[j+k+D]))

        for idx,si in X:

            for jdx,sj in Y:

                dp[i+1][idx] = (
                    dp[i+1][idx]
                    +dp[i][idx]*dp[i][jdx]*(si/(si+sj))
                )
                dp[i+1][jdx] = (
                    dp[i+1][jdx]
                    +dp[i][jdx]*dp[i][idx]*(sj/(si+sj))
                )

print(dp[-1][0])