import sys

input = sys.stdin.readline


def main():
    T = int(input())
    N = int(input())
    *C, = map(int, input().split())
    *V, = map(int, input().split())
    DP = [0]*(T+1)

    for i in range(N):
        c, v = C[i], V[i]
        while v > 0:
            for i in range(T-c, -1, -1):
                DP[i+c] = max(DP[i+c], DP[i]+v)
            v //= 2

    print(DP[-1])


if __name__ == '__main__':
    main()