n=int(input())
a=list(input().split())
b=list(input().split())
a_win=0
a_memo=0

if min(a)>=max(b):
    print('1')
    exit()
if min(b)>=max(a):
    print('0')
    exit()


for aa in a:
  for bb in b:
    if aa>=bb:
      a_memo+=1
  if a_memo > n:
    a_win+=1
  



print(round(a_win/n,4))