T=int(raw_input())
N=int(raw_input())
cs = map(int,raw_input().split())
vs= map(int,raw_input().split())
dp = [-1 for i in range(10001)]
dp[0]=0

for i in range(N):
    for j in range(10000,-1,-1):
        if dp[j]>=0:
            c=cs[i]
            v=vs[i]
            nt = j+c
            nv = dp[j]+v
            while nt <= T and v != 0:
                dp[nt] = max(dp[nt],nv)
                v/=2
                nt+=c
                nv+=v

print max(dp)