T = int(input())
N = int(input())
C = tuple(map(int, input().split()))
V = tuple(map(int, input().split()))

dp = [0] * (T + 1)
for c, v in zip(C, V):
    new_dp = dp.copy()
    u = 0
    for n in range(v.bit_length()):
        u += v >> n
        if T < c * (n + 1) - 1:
            break
        for i in range(T - c * (n + 1) + 1):
            new_dp[i + c * (n + 1)] = max(new_dp[i + c * (n + 1)], dp[i] + u)
    dp = new_dp
print(max(dp))