import numpy as np



N = int(eval(input()))

A_array = np.array([int(x) for x in input().split()])



a_array = np.sum(1/A_array)

print((1/a_array))
import numpy as np



N = int(eval(input()))

A = [int(x) for x in input().split()]



A_sum = 0

for i in A:

    A_sum += 1/i

    

print((1/A_sum))
import numpy as np

N = int(eval(input()))
A_array = np.array([int(x) for x in input().split()])
a_array = np.sum(1 / A_array)
print((1 / a_array))

import numpy as np

N = int(eval(input()))
A = [int(x) for x in input().split()]
A_sum = 0
for i in A:
    A_sum += 1 / i
print((1 / A_sum))

-A_array = np.array([int(x) for x in input().split()]) -a_array = np.sum(1 / A_array) -print((1 / a_array)) +A = [int(x) for x in input().split()] +A_sum = 0 +for i in A: +    A_sum += 1 / i +print((1 / A_sum))