import fractions

n = int(eval(input()))

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

a.sort()

if n==1:

    print((*a))

else:

    s = a[0]

    for i in range(1,n):

        s = s * a[i] / fractions.gcd(s, a[i])

    ans = 0

    for i in a:

        ans += s/i

    print((s/ans))
n = int(eval(input()))

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

ans = 0

for i in range(n):

    ans += 1/a[i]

print((1/ans))

import fractions

n = int(eval(input()))
a = list(map(int, input().split()))
a.sort()
if n == 1:
    print((*a))
else:
    s = a[0]
    for i in range(1, n):
        s = s * a[i] / fractions.gcd(s, a[i])
    ans = 0
    for i in a:
        ans += s / i
    print((s / ans))

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

-import fractions - -a.sort() -if n == 1: -    print((*a)) -else: -    s = a[0] -    for i in range(1, n): -        s = s * a[i] / fractions.gcd(s, a[i]) -    ans = 0 -    for i in a: -        ans += s / i -    print((s / ans)) +ans = 0 +for i in range(n): +    ans += 1 / a[i] +print((1 / ans))