from math import sqrt

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

S=[]
for i in range(N):
    if bool(S) and S[-1][0]/S[-1][1]>A[i]/B[i]:
        S[-1][0]+=A[i]
        S[-1][1]+=B[i]
    else:
        S.append([A[i],B[i]])

T=0
for a,b in S:
    x=max(sqrt(a/b)-1,0)
    T+=a/(1+x)+b*(1+x)

print(T)