M = int(input())
lsS = [int(input()) for i in range(1<<M)]
#全シミュレーション
lsA = [[] for i in range(1<<M)]
for i in range(1<<M):
    lsA[i].append((i,1))

for i in range(M):
    lsB = [[] for i in range(1<<(M-1-i))]
    for j in range(1<<(M-1-i)):
        for k in range(1<<i):
            v1,p1 = lsA[2*j][k]
            P = 0
            for l in range(1<<(i)):
                v2,p2 = lsA[2*j+1][l]
                P += p2*(lsS[v1]**2)/(lsS[v1]**2+lsS[v2]**2)
            P *= p1
            lsB[j].append((v1,P))

            v1,p1 = lsA[2*j+1][k]
            P = 0
            for l in range(1<<(i)):
                v2,p2 = lsA[2*j][l]
                P += p2*(lsS[v1]**2)/(lsS[v1]**2+lsS[v2]**2)
            P *= p1
            lsB[j].append((v1,P))
    lsA = lsB
print(lsA[-1][0][1])