weight,num_of_goods=input().split(' ')
weight,num_of_goods=int(weight),int(num_of_goods)
each_weight=input().split(' ')
for i in range(len(each_weight)):
	each_weight[i]=int(each_weight[i])
values=input().split(' ')
for i in range(len(values)):
	values[i]=int(values[i])

res=[]
def sol_2(W,V,weight,result):
	global res
	if weight<0:
		return 0
	if len(W)==1:

		if weight-W[0]<0:
			result=result
		else:
			result+=V[0]
		res.append(result)
	else:
		#要
		sol_2(W[1:],V[1:],weight-W[0],result+V[0])
		#不要
		sol_2(W[1:],V[1:],weight,result)
sol_2(each_weight,values,weight,0)
print("%.1f"%(max(res)*0.1))