import math
T=int(input())
N=int(input())
C=list(map(int,input().split()))
V=list(map(int,input().split()))
Z=list(zip(C,V))
Z2=Z[:]
O=0
for z in Z:
    c=z[0]
    v=z[1]
    while True:
        v=math.floor(v/2)
        if v<=0:
            break
        Z2.append((c,v))
A=[[0]*(T+1) for i in range(len(Z2)+1)]
for i in range(1,len(Z2)+1):
    for t in range(1,T+1):
        z=Z2[i-1]
        c=z[0]
        v=z[1]
        if t-c<0:
            A[i][t]=A[i-1][t]
        else:
            A[i][t]=max(A[i-1][t-c]+v,A[i-1][t])
    O=max(max(A[i]),O)
print(O)