import math
n=int(input())
a=list(map(int,input().split()))
b=list(map(int,input().split()))
c=[0]*n
asum=0
bsum=0
for i in range(n-1,-1,-1):
  asum+=a[i]
  bsum+=b[i]
  if asum>=bsum:
    c[i]=min(math.sqrt(a[i]/b[i])-1,math.sqrt(asum/bsum)-1)
currmax=0
for i in range(n):
  currmax=max(currmax,c[i])
  c[i]=currmax
ans=0
for i in range(n):
  ans+=a[i]/(1+c[i])
  ans+=b[i]*(1+c[i])
print(ans)