def main():
    import sys
    input = sys.stdin.read().split()
    idx = 0
    T = int(input[idx]); idx +=1
    N = int(input[idx]); idx +=1
    c = list(map(int, input[idx:idx+N]))
    idx +=N
    v = list(map(int, input[idx:idx+N]))
    idx +=N
    
    groups = []
    for i in range(N):
        ci = c[i]
        vi = v[i]
        options = []
        current_v = vi
        sum_val = 0
        k = 0
        while True:
            k +=1
            time = ci * k
            if time > T:
                break
            sum_val += current_v
            options.append((time, sum_val))
            if current_v ==0:
                break
            current_v = current_v //2
            if sum_val == sum_val - current_v:  # no change in next step, break
                break
        groups.append(options)
    
    dp = [-float('inf')] * (T +1)
    dp[0] = 0
    for group in groups:
        temp_dp = dp.copy()
        for time, val in group:
            for t in range(T, time-1, -1):
                if dp[t - time] + val > temp_dp[t]:
                    temp_dp[t] = dp[t - time] + val
        dp = temp_dp
    
    print(max(dp))

if __name__ == '__main__':
    main()