t = int(input())
n = int(input())
c = list(map(int, input().split()))
v = list(map(int, input().split()))

dp = {}
dp[0] = 0
for i in range(n):
  cost = c[i]
  value = 0
  cur = v[i]
  ndp = {}
  while cur > 0:
    value += cur
    for ck, cv in dp.items():
      ndp[ck] = max(ndp.get(ck, -1), cv)
      if ck + cost <= t:
        nxt = ck + cost
        ndp[nxt] = max(ndp.get(nxt, -1), cv + value)

    cost += c[i]
    cur //= 2

  dp = ndp

print(max(dp.values()))