from fractions import Fraction



n = int(eval(input()))



num_list = [Fraction(1,int(i)) for i in input().split()]



temp_list = 0

for fr in num_list:

    temp_list += fr



print((float(Fraction(temp_list.denominator,temp_list.numerator))))
n = int(eval(input()))

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



calc = 0

for i in range(n):

  calc += 1/aList[i]



print((1/calc))

from fractions import Fraction

n = int(eval(input()))
num_list = [Fraction(1, int(i)) for i in input().split()]
temp_list = 0
for fr in num_list:
    temp_list += fr
print((float(Fraction(temp_list.denominator, temp_list.numerator))))

n = int(eval(input()))
aList = list(map(int, input().split()))
calc = 0
for i in range(n):
    calc += 1 / aList[i]
print((1 / calc))

-from fractions import Fraction - -num_list = [Fraction(1, int(i)) for i in input().split()] -temp_list = 0 -for fr in num_list: -    temp_list += fr -print((float(Fraction(temp_list.denominator, temp_list.numerator)))) +aList = list(map(int, input().split())) +calc = 0 +for i in range(n): +    calc += 1 / aList[i] +print((1 / calc))