import bisect
import copy
import decimal
import fractions
import functools
import heapq
import itertools
import math
import random
import sys
from collections import Counter,deque,defaultdict
from functools import lru_cache,reduce
from heapq import heappush,heappop,heapify,heappushpop,_heappop_max,_heapify_max
def _heappush_max(heap,item):
    heap.append(item)
    heapq._siftdown_max(heap, 0, len(heap)-1)
def _heappushpop_max(heap, item):
    if heap and item < heap[0]:
        item, heap[0] = heap[0], item
        heapq._siftup_max(heap, 0)
    return item
from math import gcd as GCD
read=sys.stdin.read
readline=sys.stdin.readline
readlines=sys.stdin.readlines

N=int(readline())
P=list(map(int,readline().split()))
Q=list(map(int,readline().split()))
for i in range(N):
    P[i]=(P[i]*Q[i]/100000,Q[i]/100)
_heapify_max(P)
ans=0
pro=1
for _ in range(10**6):
    p,q=_heappop_max(P)
    ans+=pro
    pro-=p
    _heappush_max(P,(p*(1-q),q))
print(ans)