import sys
read=sys.stdin.buffer.read
readline=sys.stdin.buffer.readline
readlines=sys.stdin.buffer.readlines

t=int(readline())
n=int(readline())
c=list(map(int, readline().split()))
v=list(map(int, readline().split()))
dp=[0]*(t+1)
for x, y in zip(c, v):
    while y:
        newdp=dp[:]
        for i, z in enumerate(dp):
            if i+x>t:
                break
            newv=z+y
            if newdp[i+x]<newv:
                newdp[i+x]=newv
        dp=newdp
        y>>=1
print(dp[t])