#yuki_37

dp=[-1 for i in xrange(100000)]
t=int(raw_input())
n=int(raw_input())
c=map(int,raw_input().split())
v=map(int,raw_input().split())
dp[0]=0
res=0
for i in xrange(n):
 while v[i]:
  for j in xrange(t,c[i]-1,-1):
   if dp[j]:
    dp[j]=max(dp[j],dp[j-c[i]]+v[i])
  v[i]/=2
for i in xrange(t+1):
 res=max(dp[i],res)
print res