from collections import *
from itertools import *
from functools import *
from heapq import *
import sys,math
input = sys.stdin.readline

T = int(input())
N = int(input())
C = list(map(int,input().split()))
V = list(map(int,input().split()))
dp = [[0]*(T+2) for _ in range(N+1)]
for i in range(N):
    v = V[i]
    c = C[i]
    
    for j in range(T+1):
        dp[i+1][j] = max(dp[i][j],dp[i+1][j])
        tv = v
        sv = tv
        tj = j
        while tv:
            dp[i+1][min(tj+c,T+1)] = max(dp[i+1][min(tj+c,T+1)], dp[i][min(j,T+1)] + sv)
            tv //= 2
            sv += tv
            tj += c

ans = max(dp[-1][:T+1])

print(ans)