import numpy as np

N=int(eval(input()))



str_list = input().split(' ')

A = [int(x) for x in str_list]

A = np.array(A)

total = A.sum()

prod = A.prod()

#print( prod/( (prod/A).sum() ) )

print(( 1.0/np.sum(1.0/A) ))
N=int(eval(input()))

A=list(map(int, input().split()))



prod = 1

for ii in range(N):

    prod *= A[ii]

sum = 0

for ii in range(N):

    sum += prod//A[ii]

print((float(prod)/float(sum)))

import numpy as np

N = int(eval(input()))
str_list = input().split(" ")
A = [int(x) for x in str_list]
A = np.array(A)
total = A.sum()
prod = A.prod()
# print( prod/( (prod/A).sum() ) )
print((1.0 / np.sum(1.0 / A)))

N = int(eval(input()))
A = list(map(int, input().split()))
prod = 1
for ii in range(N):
    prod *= A[ii]
sum = 0
for ii in range(N):
    sum += prod // A[ii]
print((float(prod) / float(sum)))

-import numpy as np - -str_list = input().split(" ") -A = [int(x) for x in str_list] -A = np.array(A) -total = A.sum() -prod = A.prod() -# print( prod/( (prod/A).sum() ) ) -print((1.0 / np.sum(1.0 / A))) +A = list(map(int, input().split())) +prod = 1 +for ii in range(N): +    prod *= A[ii] +sum = 0 +for ii in range(N): +    sum += prod // A[ii] +print((float(prod) / float(sum)))