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):
    a=A[i]; b=B[i]
    while bool(S) and S[-1][0]/S[-1][1]>a/b:
        Sa,Sb=S.pop()
        a+=Sa; b+=Sb
    S.append((a,b))

T=0
for a,b in S:
    if a>b:
        T+=2*sqrt(a*b)
    else:
        T+=a+b

print(T)