M = int(input())
N = 1 << M
S = [int(input()) for _ in range(N)]
S2 = [s * s for s in S]
X = [[0] * N for _ in range(M + 1)]
for i in range(N):
    X[0][i] = 1
for i in range(M):
    unit = 1 << i
    block = 2 * unit
    for j in range(N // unit):
        rj = j + (-1) ** j
        for k in range(unit):
            a = j * unit + k
            for l in range(unit):
                b = rj * unit + l
                X[i + 1][a] += S2[a] / (S2[a] + S2[b]) * X[i][b]
            X[i + 1][a] *= X[i][a]
print(X[-1][0])