#yuki37

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