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))
N = int(eval(input()))

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

N = int(eval(input()))
A = list(map(int, input().split()))
A_sum = 0
for i in A:
    A_sum += 1 / i
print((1 / A_sum))

-import numpy as np - -A = [int(x) for x in input().split()] +A = list(map(int, input().split()))