import math

def dfs(s, n):
    ret = [0.0] * n
    if n == 1:
        ret[0] = 1
        return ret
    
    a = dfs(s, n // 2)
    b = dfs(s + n // 2, n // 2)
    for i in range(len(a)):
        for j in range(len(b)):
            p = a[i] * b[j]
            ap = s + i
            bp = s + n // 2 + j
            ret[i] += p * params[ap] * params[ap] / (params[ap] * params[ap] + params[bp] * params[bp])
            ret[n // 2 + j] += p * params[bp] * params[bp] / (params[ap] * params[ap] + params[bp] * params[bp])
    return ret

M = int(input())
mem = int(math.pow(2, M))
params = []

for _ in range(mem):
    params.append(int(input()))
    
ans = dfs(0, mem)
print(ans[0])