#!/usr/bin/env python3.8
# %%
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines
import numpy as np

# %%
T = int(readline())
N = int(readline())
C = tuple(map(int, readline().split()))
V = tuple(map(int, readline().split()))


# %%
dp = np.zeros(T + 1, np.int64)
for c, v in zip(C, V):
    newdp = dp.copy()
    total_c = 0
    total_v = 0
    while v:
        total_c += c
        total_v += v
        v //= 2
        if total_c > T:
            break
        np.maximum(newdp[total_c:], dp[:-total_c] + total_v, out=newdp[total_c:])
    dp = newdp


# %%
print(dp.max())