# https://yukicoder.me/problems/no/3711



def main():
    N, M = map(int, input().split())
    U = list(map(int, input().split()))
    T = list(map(int, input().split()))

    sum_t = sum(T)

    # 天ぷらの選択についてのdp

    dp = [False] * (sum_t + 1)
    dp[0] = True
    for t in T:
        for m in reversed(range(sum_t + 1)):
            if m + t <= sum_t:
                dp[m + t] |= dp[m]

    answer_set = set()
    for u in U:
        for m in range(sum_t + 1):
            if dp[m]:
                ans = u + m
                answer_set.add(ans)

    print(len(answer_set))

if __name__ == "__main__":
    main()