Given is a sequence of N integers A_1, \ldots, A_N.
Find the (multiplicative) inverse of the sum of the inverses of these numbers, \frac{1}{\frac{1}{A_1} + \ldots + \frac{1}{A_N}}.

-----Constraints-----
 - 1 \leq N \leq 100
 - 1 \leq A_i \leq 1000

-----Input-----
Input is given from Standard Input in the following format:
N
A_1 A_2 \ldots A_N

-----Output-----
Print a decimal number (or an integer) representing the value of \frac{1}{\frac{1}{A_1} + \ldots + \frac{1}{A_N}}.
Your output will be judged correct when its absolute or relative error from the judge's output is at most 10^{-5}.

-----Sample Input-----
2
10 30

-----Sample Output-----
7.5

\frac{1}{\frac{1}{10} + \frac{1}{30}} = \frac{1}{\frac{4}{30}} = \frac{30}{4} = 7.5.
Printing 7.50001, 7.49999, and so on will also be accepted.

Difficulty: introductory

Starter code:

Solutions:
n=int(input())
a=list(map(lambda x:1/int(x),input().split()))
print(1/sum(a))

n = int(input())
A = list(map(int, input().split()))

total = 0

for i in range(n):
    total += 1/A[i]
    
print(1/total)

N = float(input())
A = [1/f for f in map(float, input().split())]
print(1/sum(A))

n = int(input())
list_a = [int(i) for i in input().split()]
ans = 0.0
for i in range(0, n):
    ans += 1 / list_a[i]
    if i == n - 1: ans = 1 / ans
print(ans)

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


from fractions import Fraction
from typing import List


def answer(n: int, a: List[int]) -> float:
    f = Fraction(1, sum(Fraction(1, i) for i in a))
    return f.numerator / f.denominator


def main():
    n = int(input())
    a = list(map(int, input().split()))
    print((answer(n, a)))


def __starting_point():
    main()

__starting_point()

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

print(float(1/sum))

N = int(input())
A = list(map(int, input().split()))
ans = 0
for a in A:
    if a == 0:
        continue
    ans += 1 / a
if ans == 0:
    print((0))
else:
    print((1 / ans))


# import math
# import statistics
# import itertools
a=int(input())
#b,c=int(input()),int(input())
# c=[]
# for i in a:
#     c.append(int(i))
# e1,e2,e3,e4 = map(int,input().split())
f = list(map(int,input().split()))
# g = [int(input()) for _ in range(a)]
bunbo=0
for i in range(len(f)):
    bunbo+=1/f[i]
print(1/bunbo)

N = int(input())
A = list(map(int, input().split()))
check = 0
from decimal import Decimal
for i in range(N):
  check += Decimal(1/A[i])
ans = Decimal(1/check)
print(ans)

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

n=int(input())
a=list(map(lambda x:1/int(x),input().split()))
print(1/sum(a))

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

print(float(1/sum))

import math
from functools import reduce

def lcm_base(x, y):
    return (x * y) // math.gcd(x, y)

def lcm(*a):
    return reduce(lcm_base, a, 1)

def lcm_list(a):
    return reduce(lcm_base, a, 1)

n = int(input())
a = list(map(int, input().split()))
mom = lcm_list(a)
a.sort()
num = []
for i in range(n):
    num.append(mom // a[i])
print(mom / sum(num))

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

N = int(input())
A = list(map(int,input().split()))

ans = 0
for i in A:
    ans += 1/i

print(1/ans)

_ = input()
a = list(map(int,input().split()))
ans = 0;
for i in a:
  ans += 1/i
print(1/ans)

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


n = int(input())
a = list(map(int, input().split()))
b = 0
for i in a:
    b += 1 / i
print(1 / b)

from sys import stdin

n = int(stdin.readline().rstrip())
A = [int(a) for a in stdin.readline().rstrip().split()]

A = [float(a) for a in A]

total = 0.

for a in A:
    total += 1/a

print(1/total)

N=int(input())
A=list(map(int,input().split()))
print(1/sum([1/a for a in A]))

import numpy as np
N,*A=map(int,open(0).read().split())
print(1/np.sum(1/np.array(A)))

N = int(input())
lsA = list(map(int,input().split()))
d = 0
for i in range(N):
    d += 1/lsA[i]
print(1/d)

n=int(input())
a=list(map(int,input().split()))
ans=0.0
for i in range(n):
  ans=ans+1.0/a[i]
ans=1.0/ans
print(ans)

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

n = int(input())
a = list(map(int, input().split()))
x = sum([1/a[i] for i in range(n)])
print(1/x)

n=int(input())
a=list(map(int, input().split()))
d=0
for i in a:
  d+=1/i
print(1/d)

import numpy as np
n=int(input())
l= [np.array(input().split() ,dtype=np.int64)]

l2=[]
for i in range(len(l)):
    l2.append(1/(l[i]))
    sum1=np.sum(l2) 
    ans=1/(sum1)
print(ans)

N=int(input())
A_lis=list(map(int,input().split()))
a=0        
for i in A_lis:
   a += 1/i
ans = 1/a
print(ans)  

# coding: utf-8

num = int(input())
total = 0
str = input().split()
table = list(str)
for i in range(num):
    total += 1 / int(table[i])

total = 1 / total
print(total)

n = int(input())
A = list(map(int, input().split()))

ans = 0

for a in A:
    ans += 1/a

print(1/ans)

N = int(input())
A = list(map(int, input().split()))
 
s = 0
for i in range(N):
  s += 1 / A[i]

print(1/s)

N = int(input())
A = list(map(int, input().split()))

print(1/sum([1/a for a in A]))

N = int(input())
A = list(map(int,input().split()))
asum = 0

for i in range(N):
    asum += 1/A[i]

print(1/asum)

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

import numpy as np

# N, Aを取得
N = int(input())
A = np.array(list(map(int, input().split())))

# 各Aの逆数の和の逆数
result = 1 / np.sum(1.0 / A)

# 結果を出力
print(result)

n=int(input())
A=list(map(int,input().split()))
ans = 0
for a in A:
  ans += 1/a
print(1/ans)

N = int(input())
A = list(map(int, input().split()))

rev = 0
for i in range(N):
  rev += 1 / A[i]
print(1 / rev)

N = int(input())
A = list(map(int, input().split()))

tmp = 0
for i in A:
    tmp += 1/i
print(1/tmp)

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

n = int(input())
li = list(map(int,input().split()))
li1 = []

for i in li:
    li1.append(1/i)

su = sum(li1)
print((1/su))


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

print(1/sum(list(map(lambda x: 1/x, a))))

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

ans = 0
for i in a:
    ans += 1 / i
print(1 / ans)

N = int(input())
Alst = list(map(int, input().split()))
ans = 0
for i in Alst:
    ans += 1/i

print(1/ans)

n = int(input())
lis = list(map(int,input().split()))
total = 0

for i in lis:
  x = 1 / i
  total += x

print((1 / total))


input();print(1/sum(1/i for i in map(int,input().split())))

n=int(input())

a_list=[1/int(i) for i in input().split()]
ans=1/sum(a_list)

print(ans)


import numpy as np

# N,Aを取得
N = int(input())
A = np.array(list(map(int,input().split())))

# 逆数の和を取得する
result = 1 / np.sum(1 / A)

print(result)

n = int(input())

s = list(map(int, input().split()))
t = []
v = 0

for i in range(n):
  c = 1/s[i]
  t.append(c)
  
for j in range(n):
  v += t[j]
  
ans = 1/v

print(ans)

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


n = int(input())
a = [1/int(x) for x in input().split()]
print((1/sum(a)))


# ABC138

N = int(input())
A = list(map(int, input().split()))
bunbo = 0

for a in A:
    bunbo += 1/a
print((1/bunbo))


def solve():
    N = int(input())
    A = list(map(int, input().split()))
    ans = 0
    A = [1 / a for a in A]
    print((1 / sum(A)))
    return

solve()


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

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

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

N=int(input())
A=list(map(int, input().split()))
Arev=[]

for a in A:
	Arev.append(1/a)

print((1/sum(Arev)))


# 入力から逆数の総和を取りその逆数を出力する
input()
print(1 / sum(map(lambda x: 1 / int(x), input().split())))

a = int(input())
b = list(map(int,input().split()))
A = 1
B = 0
for i in range(a):
  A *= b[i]
for i in range(a):
  B += A/b[i]
print(A/B)

N = int(input())
A = list(map(int, input().split()))

lst = []
for i in A:
    lst.append(1/i)
ans = 1 / (sum(lst))
print(ans)

n = int(input())
A = list(map(int, input().split()))
s = 0

for i in range(n):
    s += 1/A[i]
print((1/s))


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

prod = a[0]
for A in a[1:]:
    prod *= A

sumprod = 0
for A in a:
    sumprod += prod // A

print(prod/sumprod)

import numpy as np
N = int(input())
a = list(map(float, input().split()))
a_rev = np.reciprocal(a)
a_rev_sum = np.sum(a_rev)
print(1/a_rev_sum)

def mapt(fn, *args):
    return tuple(map(fn, *args))


def Input():
    return mapt(int, input().split(" "))


def aaa(num):
    return 1/num

def main():
    n = int(input())
    a = Input()
    ans = 1 / sum(aaa(i) for i in a)
    print(ans)
main()

N = int(input())
A = list(map(int, input().split()))

nom = 1
denom = A[0]

for i in range(1, N):
    nom = nom * A[i] + denom
    denom = denom * A[i]

print(denom / nom)

# 入力の整数列を取得する
n = int(input())
nums = map(int, input().split())

# 逆数のリストを作成する
re_nums = [1 / num  for num in nums]

# 逆数のリストの総和の逆数を求める
print(1 / sum(re_nums))

N = int(input())
A = list(map(int, input().split()))
B = [1/i for i in A]
Bs = sum(B)
ans = 1 / Bs
print(ans)

N = int(input())
A = list(map(int, input().split()))
ans = 0
for a in A:
    ans += 1 / a

ans = 1 / ans
print(ans)

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

ans = 0

for i in range(n):
  ans += 1/a[i]
  
print(1/ans)

#ABC138 B

N = int(input())
A = list(map(int,input().split()))
S = 0
for i in range(N):
    S += 1/A[i]

print(1/S)

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

ans = 1 / ans
print(ans)

n = int(input())
a = [1 / int(s) for s in input().split()]


print((1 / sum(a)))


N = int(input())
A = list(map(int, input().split()))

gyakusuu = 0
for i in A:
    gyakusuu += 1 / i

ans = 1/gyakusuu

print(ans)

n = int(input())
print(1 / sum([1 / int(i) for i in input().split()]))

# 問題：https://atcoder.jp/contests/abc138/tasks/abc138_b

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

res = 0
for i in range(n):
    res += 1 / a[i]
res = 1 / res

print(res)


s = int(input())
a = [(1/int(i)) for i in input().split()]
print(1/sum(a))

N = int(input())
A = list(map(int,input().split()))

bunbo = 0

for i in range(N):
    bunbo += 1/A[i]
    
print(1/bunbo)

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

N=int(input())
A=list(map(int,input().split()))
print((1/sum(1/a for a in A)))


# 入力を受け通る
N=int(input())
A=list(map(int,input().split()))

# 逆数の総和を求める
tmp=0
for a in A:
    tmp += 1/a

# 総和の逆数を求める
ret=1/tmp

print(ret)

N=int(input())
d=[int(s) for s in input().split()]
x=1
for i in range(N):
    x=x*d[i]
y=0
for i in range(N):
    y+=int(x/d[i])
print(x/y)

n=int(input())
a=[int(x) for x in input().split()]
c=0
for i in range(n):
    c+=1/a[i]
print(1/c)

n = int(input())
a = list(map(int,input().split()))
b = []

for x in a :
  b.append(1/x)
  
c = sum(b)
ans = 1/c
print(ans)


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

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

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

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

ans = 0
for i in a:
    ans += 1 / i

ans = 1 / ans

print(ans)


n = int(input())
print(1/sum([1/int(n) for n in input().split()]))

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

n = int(input())
A = list(map(int, input().split()))

ans = 0
for a in A:
  ans += 1 / a
print(1/ans)

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

N = int(input())
A = map(int, input().split())
print('{:.16g}'.format(1/sum(1/x for x in A)))

n=int(input())
a=list(map(int,input().split()))
kei=0.0
for i in range(n):
    kei += 1/a[i]
print((float)(1/kei))

n=int(input())
a=list(map(int,input().split()))
s=0

for i in range(n):
  s+=1/a[i]
print(1/s)

import re
import sys
import math
import itertools
import bisect
from copy import copy
from collections import deque,Counter
from decimal import Decimal
import functools
def v(): return input()
def k(): return int(input())
def S(): return input().split()
def I(): return map(int,input().split())
def X(): return list(input())
def L(): return list(input().split())
def l(): return list(map(int,input().split()))
def lcm(a,b): return a*b//math.gcd(a,b)
sys.setrecursionlimit(10 ** 6)
mod = 10**9+7
cnt = 0
ans = 0
inf = float("inf")
al = "abcdefghijklmnopqrstuvwxyz"
AL = al.upper()

N = k()
A = l()
for i in A:
    ans += 1/i
 
ans = 1/ans
print(ans)

# 入力の整数列を取得する
n = int(input())
nums = list(map(int, input().split()))

# 逆数のリストを作成する
re_nums = [1 / num  for num in nums]

# 逆数のリストの総和の逆数を求める
print(1 / sum(re_nums))

n = int(input())
a = list(map(int,input().split()))
targ = 0
for j in a:
	targ += 1/j
print(1/targ)

def resolve():
    n = int(input())
    a = [1/(int(i)) for i in input().split()]
    print(1/sum(a))
resolve()

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