import sys
input=lambda:sys.stdin.readline().rstrip()
def knapsack(items,capacity):
    N=len(items)
    dp=[[0 for i in range(capacity+1)] for j in range(N+1)]
    for i in range(N):
        for j in range(min(capacity+1,items[i][0])):
            dp[i+1][j]=dp[i][j]
        for j in range(items[i][0],capacity+1):
            dp[i+1][j]=max(dp[i][j],dp[i][j-items[i][0]]+items[i][1])
    return dp[N][capacity]
T,N=[int(input()) for i in range(2)]
C=list(map(int,input().split()))
V=list(map(int,input().split()))
items=[]
for i in range(N):
	while V[i]:
		items.append([C[i],V[i]])
		V[i]//=2
print(knapsack(items,T))