import sys

input = sys.stdin.readline



N = int(eval(input()))

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



c = 0

for i in lis_a:

    c += 1/i



print((1/c))

n=int(eval(input()))

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

s=0

for i in range(n):

      s+=1/a[i]

print((1/s))
import sys

input = sys.stdin.readline
N = int(eval(input()))
lis_a = list(map(int, input().split()))
c = 0
for i in lis_a:
    c += 1 / i
print((1 / c))

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

-import sys - -input = sys.stdin.readline -N = int(eval(input())) -lis_a = list(map(int, input().split())) -c = 0 -for i in lis_a: -    c += 1 / i -print((1 / c)) +n = int(eval(input())) +a = list(map(int, input().split())) +s = 0 +for i in range(n): +    s += 1 / a[i] +print((1 / s))